Question: 1. In [Sherlock Holmes: A Game of Shadows](http://www.imdb.com/title/tt1515091/), why does Moriarty want a sniper to additionally shoot the man in the hotel? Was the bomb not enough?
2. In the first movie, the purpose of Professor Moriarty was stealing the remote control, but it is not mentioned in the second movie at all! Was there a point?

Answer: 
The bomb actually was a coverup to the assassination of the designated target. If the specified target alone is killed with the bullet, Moriarty might have deduced that any of the threads for plotting the murder could be traced back to him or his accomplices. So, he wanted to cover it up with a bomb to blow up everyone to spark a political conspiracy rather than making it a single person assassination hit.

Your second question is correct. I don't recollect that aspect being used in the second movie, but I think the director used it as a major plot element to introduce Moriarty to viewers — after all, Moriarty is Holmes's greatest adversary.
The purpose of the bomb was threefold:

1. To conceal the fact that a single person in the room was to be killed
2. To inflame passions in the country's involved to ratchet up tensions for Moriarty's desired worldwide conflict
3. To destroy any trace evidence that any of the above had occurred.

When the explosion is shown from the outside of the building, it is clear that the bomb created a great deal of heat and open flames as well as a powerful explosion. It also clearly destroys all of the windows facing the protagonists. In fact, the room and building should have still be on fire when the protagonists entered given the size of the explosion shown and any human remains should have mangled or destroyed making Holmes' deductions impossible.

The remote control from the first film seems to to fit in with the numerous weapon's technologies been built by Moriarty's vast web of companies. When for some reason the second film's narrative diverged from the ending of the first, the need to explain the remote and how it could have been used (decades before any such device was built in reality) seems to have dropped in favor of telling the new story.