1) replace breather pipes. unlikely to be cat if it runs better with oil filler cap removed.
2) no need to say anything to this
3) sand pipe down see how bad it's rusted and paint if there's enough substance left, if not replace
4) fairly simple, you only need a set of spring compressors - can post some instructions if you're struggling. worth checking condition of your shocks... if they are bad would replace them as well, saves you time and upper strut mounts are easier to replace with the whole strut out (rather than compressing springs and then fiddling old one out and new one in)
5) rear shocks should be reasonably cheap, try gsf or ecp (forum discount 25%)
6) rear bearing are easy to replace, you just need a "tool" to get the old ones out and the new ones in
tool = short piece of pipe with suitable diameter - I used a bit of round alu waste trimmed to right diameter on a lathe.
"Adjusting" a worn bearing is rubbish idea. Not going to last and a new FEBI set is 10£ plus a tube of bearing grease = 5£
