Apart from restoring the old order, another major theme of the congress of Vienna was to balance to power dynamics of Europe. Everybody had witnessed how one country managed to almost conquere to entire continent, so in order to avoid further wars, the congress members wanted to create a new power balance. For example, France lost her conquests, was restored into her old border from before the revolution and all the French puppet states like the Kingdom of Westphalia were dissolved, whereas Prussia gained new territories, most notably the various smaller Rhineland territories which bordered France, so that they would be under the influence of a more powerful country and would not be easily overtaken by France again. However, while Prussia gained these new areas, she was also forced to give up others like some of her polish territories that were given to Russia. So, in short: These new territorial distributions took place to guarantee the power balance in Europe.

In Regards to your second question: During the Liberation wars against Napoleon a certain patriotic enthusiasm swept over the German states. In his proclamation "An Mein Volk"/"To My People", which called his people to arms, the Prussian King Frederick William III didn't just appealed to his subjects as Prussians, but also as Germans. Although very slowly, the people started to think of themselves as Germans rather than as Bavarians, Hessians or Swabians. In the coming years the people's demand for one united Germany would grow more and more and finally culminate in the revolution of 1848. However, while the want of a united Germany existed and grew whitin the populated the rulers of the smaller and bigger German states as well as the foreign sovereigns were strongly opposed to this idea. After all, a united Germany would be to strong to maintain the newly created power balance of Europe and the monarchs of the smaller German states feared that they would lose all their powers in their countries, which is also the reason why they didn't want to restore the Holy Roman Empire. The HRE had one emperor that had certain powers over all the German states, but the rulers of these states didn't want to give up their newly gained sovereignty.

Despite the vast disagreements among the participants of the congress of Vienna, they all had one common enemy: Revolution. So, to oppose further uprisings against the old order among the population, the countries of the congress pledged themselves to solidarity among each other (at least in this issue). That was also the case for all the bigger and smaller German states. While an restoration of the HRE wasn't part of a serious ambition of the congress, a similar construct to the HRE was created. The German states formed the German Confederation, which just like the HRE was a loose association of German-speaking states, but it didn't have one Emperor, that stood above the other rulers, like it's predecessor. The main task of the defensive German Confederation was to improve and stabilize the economies of the various members as well as to protect the states against foreign invaders and inner turmoil and revolutions.