This is something that I've always wondered about. Were the biblical Romans the same as modern-day Romans? How much control did they have over the government, and why?
To answer you question on ethnicity: Senior roman officials, such as Pilate himself, would likely have been Italians - although we can't be certain even of that. When the Bible talks about more junior administrators or soldiers, the picture becomes much more muddled.
Soldiers illustrate the problem nicely (they are, handily, also some of people in the Roman empire which have attracted most scholarship).
Roman soldiers at the turn of the century were divided into two main classes - Legionnaires and Auxilia. Legionnaires were the Roman "state troops". They were all Roman citizens, and had signed up to serve a fixed term of twenty-odd years. Yet by the turn of the century Roman citizenship is not equivalent to "born in Italy", having been extended incrementally to many natives of territories that had been incorporated into the republic and empire. Legionnaires came, as far as we're aware, almost entirely from the working classes. They signed up for a hard life in the army, and were rewarded with grants of land and capital. It was a way by which a poor young laborer might secure a future for himself and his descendants. Thus full legions and replacement legionnaires were recruited wherever Roman citizens - indeed many legions got their names from the regions where they had originally been recruited.
Just as an example - take the centurion who famously guarded Jesus on the cross (Mark 15:44-45) . The title centurion would indicate a fairly senior serving legionary officer, presumably in command of a party of legionnaires. Now, we know that there was no legion permanently stationed in Jerusalem at this time. The "Roman" soldiers there on a day-to-day basis were likely of another class entirely, namely the auxilia - more on which below. If we presume that there really were serving legionnaires present, then they would likely have been seconded to Jerusalem as a detachment from another unit. Knowing that Pontius Pilate, as prefect of Judaea, was subordinate to the Roman governor of Syria, we may assume that this was likely a unit from here - possibly stationed in or around Damascus or Antioch. Legionary records are very far from complete, but one likely candidate for such a unit would be III Gallica (although I've seen speculation of other legions as well).
Even if we assume that the soldiers in question were indeed serving in Legio III Gallica, we have problems determining their origins. Legio III, as its name implies, was originally raised in Gaul (which covered both modern day France, parts of Belgium and Northern Italy), but by the time of the crucifixion (again assuming that it took place a couple of decades after the turn of the century) it had been stationed in Syria for at least a generation. Although it had probably received some new recruits from Gaul in that time, most of the replacement soldiers making up the ranks would probably have been recruited closer to hand - modern day Turkey, Greece or Syria itself seems quite possible.
All of this is predicated on the soldiers in question being legionnaires, though. In fact, given that such forces only served intermittently in Jerusalem at the time, many soldiers described in the Bible as "Roman" are more likely to have been of the auxilia.
The auxilia - meaning "little helpers" - were the non-citizen soldiery recruited to the Roman army. They served in smaller units, denoted cohorts, and served terms roughly similar to those of legionnaires. Their pay was worse, but after completing their period of service they were granted Roman citizenship (thus their sons could join the Legions, if they so wanted). Contrary to popular opinion, an auxilia soldier did not necessarily differ too much from a legionnaire in appearance. They often used similar equipment, did similar jobs and were as numerous - if not more - as legionnaires. It is not surprising that to many local observers - including some of the authors of the Bible - they would indeed have been seen as "Romans".
Roman standard operating procedure was to recruit auxilia soldiers from a single province, and then ship them off to serve elsewhere in the empire. Just as an ironic example, we have evidence from Hadrian's wall of units Iraqi soldiers serving there. Thus auxilia soldiers stationed in Palestine at the time of Christ could have been from anywhere in the Roman world, except for Italy (where most inhabitants would have been Roman citizens, and thus eligible to join the legions instead) and Judaea (because soldiers recruited from there would likely have been sent to serve elsewhere). Yet there is another possibility. By the time of Jesus' death, the Romans had only recently (within a few decades or so) imposed direct rule of the region. Some of the forces serving under Pilate may possibly have been the remains of units that had served under the deposed local king, Herod. If so, there is a possibility that they may have been recruited locally.
So there - many of the people described in the Bible as Romans might well have been Italians - especially among the higher ranked officials - but there is also a strong possibility that they may have been from elsewhere in the Roman Empire. In most cases we just don't know.
The Romans you find in the Bible were of Italian origin. Starting from the 4th century BC the inhabitants of the city of Rome, in league with other Italian cities under their hegemony, started to expand and conquer the peninsula of Italy. As Roman control of Italy expanded it came into conflict with other empires of the time Frist Carthage, who would fight Rome in 3 wars which by their end would take Roman power into modern Spain, Portugal, and Tunisia. Next the Hellenistic (Greek) kingdoms that were the states left in the wake of Alexander the Great came into conflict with Rome, which lead Roman armies eastwards into Greece, Turkey, Syria, and modern Israel. Many other places to came uder Either direct Roman Control or indirect Roman influence as client states. By the life of Jesus the Roman Empire would look like this: http://academic.udayton.edu/williamschuerman/Roman_empire_14_ad.jpg
Were they the same as modern Roman? By which I assume you mean the modern people who live in Rome. Well yes and no, in the 2000 or so years since the life of Christ there has been many changes in history and movements of people. Over the course of time the culture of Italy and it's language have evolved. So the people of Rome today aren't the same as their Ancient Roman ancestors though the may be descended from them.
Lastly how much control did they have over the governement? By which I assume you mean the local government of Judea (what they called the region we call Israel today). Well this varied over time, from 63 BC when the Roman first establish their presence in the region until 4 BC the Judea was Ruled by kings, first of the Hasmonean dynasty and the the Herodians (You may be familiar with Herod the great in the Bible.) These kings were clients of the Roman state, mostly autonomous to rule as they wished as long as they remained friendly with Rome, provide some money, support in time of war, etc. After Herod the Great died Judea was partitioned to be ruled by his sons, and then in AD 6 The Romans took over more direct control of the region, installing a governor. The Romans were largely content to let the Jews live as they had as long as they paid their taxes to Rome (which they resented), and didn't cause any trouble for Rome. This is why Jesus was crucified, the Roman couldn't care less that the Jewish authorities considered him a blasphemer, but the claim of him being a Messiah, a king of the Jews who would free them from oppression (by the Romans) well that was a serious concern for Rome.
