I would do fully forged titanium bolts for mission critical areas and any old corroded cables and housing should be replaced along with any bar tape anywhere because you want to inspect every inch of that bar. Sweat can be corrosive as you have seen but having it sit soaked into bar tape can do some damage to bars and is also just gross and cleaning the tape is fine for newer tape you have installed (or had installed by someone) but unknown tape is a no-go.

Basically any used bike you buy should have a full overhaul done to it as you have no idea what was done or not done to it before you got it and the desire to ride right when you get it will quickly be lost when down the road you have problems that turn into bigger ones (Any Harvey Danger fans?) I had to cut out a 7400 Dura Ace French threaded bottom bracket from a bike which hurt so bad I cannot even explain. I bet it was already seized at the time of purchase but I couldn't tell you because I was more excited to ride it right away than actually do it all properly and do an overhaul.