I used to own an exhaust shop for 5 years...and I swear by PB Blaster...nothing worse than changing rusty/corroded/burned nuts/bolts/studs on donuts/manifolds/headers/catalytic convertors and rusty old exhaust hangers.
As for your lift, you should be done by now, but if not....don't rush it. It's better for it to take a few days to get it done right....than to rush it and risk tearing up more stuff in the long run. No job, like this, hardly EVER goes as planned. I've lifted some vehicles that looked like they'd sat in water for 3 months....and every bolt, somehow, came loose. I've also done some that the bolts still looked to be in pretty good shape...and for no explainable reason...other than fate....they BROKE ! All in all...when you get it done, nothing beats the satisfaction and knowledge gained by having done it yourself. IMHO anyways.
Good Luck
Aron