Hi flash, good choice of truck. I have a 2wd slash and it was brushed when I got it and I ran it on 2s lipo with no problems before switching to brushless! I've had no problems with my servo being hit by anything so wouldn't worry about it. The stock bearings were ok for a while but the rubber seal soon came off allowing dirt in so replaced them but defiantly got my money's worth out of the stock ones first. As for shocks everyone says buy powerstrokes but I couldn't afford them so I went with traxxas big bores but they didn't make much difference so was gutted, I have now put the traxxas lcg chassis on it and it's amazing! With the big bores on the truck is very stable(havent rolled it since fitting the lcg) and instead of under steering really bad like before it digs into turns now and kicks the rear end round nicely. I'm still running stock tyres on mine and they are good enough for bashing.
Have fun and think about the lcg chassis! It's the best thing I've done to my slash.