Beginner questions

What is your budget on every thing? Yes you can make your own spacers, and it depends if you have time or just want to get it over with and spend the money on the Ares.
I would suggest a firefly bucking and hop up, the stock hop up needs to be replaced now or you'll just have to do it later. Depending on your budget for a scope, I would suggest the Vism 2-10x50 or the 4-16x50 scope as they are rugged and don't cost all that much ($170-$190) then there are some Leupold replicas out there like the M3 3.5-10x50 for $80.
As for upgrades, look in the sticky's for more info on them as I don't know many other than the LRB mod and top dead center mod that you can do. New trigger is also needed.

A common misconception is that a tighter bore gives higher accuracy, that's not true. For long range shooting, a 6.05mm in a 455mm length is best. There is a thread on here titled 'Inner Barrels Resolved', it should clear some things up about barrels. I have a stock hop up chamber and bucking in my MB06, also made by Well, it works amazingly. Barrel spacers are pretty easy to make. There are probably threads on here that will tell you how to make them, or just look it up on YouTube. As for scopes, what's your budget? Barska and Nikon make good scopes.