Realy hard to say if 61cm is right size, there is a fitting guide at wrenchscience you can check out. This is not the end all be all of getting right size bike but will give you a starting point.
Yes I added a brake but alot do not, I suggest one even if you don't use it. Gearing really depends on you're fitness etc.. and the terrain you will be riding.
I have 49x17 on one and 48x19,17 (flip flop hub)on another.