Do you mean in the short or long term?

In the short term they undoubtedly hindered some of the trade, that's natural during the course of the war. Ideas and culture were exchanged quite a bit and in fact Alexander made it his goal to meld and blend together a multitude of cultures and went so far as to have his own officers and soldiers marry Persian wives to accomplish it.

In the long term it undoubtedly increased the exchange of ideas, culture, and trade. Even following his death and the rather quick disintegration of his Empire the true legacy of Alexander could be felt. Perhaps a better way of demonstrating this is with the massive amount of Greek influence on the various kingdoms like the Ptolemaic Egypt or Seleucid Empire. However, both of those kingdoms also retained much of the culture of the previous dynasties and that blend is reflective of the combination of the cultures that Alexander envisioned. Alexander himself would take a Persian wife and even have a child with her before his death.

In a word, yes. Alexander came from Macedonia, which was Hellenistic. They had adopted many Greek customs and traditions. When Alexander conquered an area, he left some soldiers behind to keep the peace and improve stability. These soldiers spread their native Hellenistic beliefs to many parts of Egypt, Turkey, and the late Persian Empire. When Alexander died in Babylon, he had left Hellenistic governors and officials across his conquered territories. When the new Egyptian, Seclude, and Greek Empires came to be after a period of fighting which included the Macedonian Civil War and the Lamian War. Hellenistic ideas created a cultural trend called Hellenization that affected Arabic technology and culture to this day, not including all the other titles he conquered. It's a very interesting subject, one which would be good to learn a little about to get a grasp on ancient cultures. Sorry if I didn't answer your question or if I got something wrong, I'm new at this.

http://www.historyofmacedonia.org/AncientMacedonia/AlexandertheGreat.html

http://www.biography.com/people/alexander-the-great-9180468

http://www.ancient.eu.com/Alexander_the_Great/

http://www.metmuseum.org/toah/hd/alex/hd_alex.htm

http://www.britannica.com/EBchecked/topic/260307/Hellenistic-Age

The ongoing presence of the Greco-Bactrian and Greco-Indian kingdoms on the subcontinent does seem to have led to increased contact between India and the Mediterranean. It's been ages since I read it, but you might want to check out WW Tarn's The Greeks in Bactria and India. It was a real eye-opener for me. I was totally unaware of the extent of Greek influence east of the Seleucids.

Questions like this are unfortunately difficult to answer with much accuracy. Our sources on the life of Alexander are not great, Appian is useful but not firsthand by any means. Despite that, it is quite clear that there was an increased exchange of ideas east to west and west to east during and after Alexander's conquests. Alexander was famous for setting cities as conquered, leaving behind a massive number of hellenistic settlements in his wake, most of which were designed in greek style (hippodamian, i.e. orthogonal, with all the necessary accoutrements of Greek society including gymnasia, theatres, temples, and agoras). These were incredibly far reaching, Ai-Khanoum is perhaps the best example of the phenomenon and is worth looking up if you're interested. At the same time, Alexander took on more Persian traits as his conquests continued (wearing of the diadem, enforcing prostration, preserving Persian structures of rule aka satrapy). His army and those of the diadochoi following him also swelled their ranks with asian forces, facilitating what must have been an environment ripe with cultural exchange. The Seleucid empire famously went to war with Bactrian elephants, for instance. Perhaps the best example of the fusion of cultures that Alexander's conquests facilitated are sites like Nemrut Dagi, which are definitely worth looking up if you get the chance. At Nemrut, the King of Commagene (a territory in SE Asia Minor) erected a massive monument that wildly blended Zoroastrian, Greek, and other gods - Ahuramazd-Zeus, Vahagn-Herakles, and Mihr-Apollo-Mithras to name several. Though 300 years after his life, the monument at Nemrut Dagi reveal a degree of cultural fusion that was in large part due to the fallout of Alexander's conquests and the Hellenistic empires that once ruled the region.