I like the Compressor, verbs and EQ in Sonar and if you need anything else there is always Waves Gold. Expensive but with that and Autotune there is not much you cant do.

I prefer, when ever possible to use good old fashioned audio rather than VSTs and Midi (even if it is recorded direct) and get the source as close to what I want as possible. However with drums this is difficult. I guess you will just have to experiment and see what works for you.

ALso, you maybe better off with a one or two channel pre amp / channel strip rather than a mixer. Mixers are great for mixing lots of things together however unless you have lots of things going on at once, they can end up being largely redundant. Check out second hand Behringer voice master pro for big bang for buck. I use a Focusrite Platinum Voice Master Pro and love it however it is a little more expensive.

SM57s and SM58s are a great choice however if you have the channel strip a Behringer Large diaphragm condenser will sound not only different but also really nice on instruments as well as vocals. My current fave mic is a Shure KSM44. It is not a U87 but is about 5 times cheaper !