reusing the manifold shouldn't be an issue. if the studs are broken at the doughnut, grind them flat with the manifold, center punch them and drill out starting out small and work up till you just see the threads. Then you should be able to use a tap and chase the threads out. go back with stainless hardware and use some high temp anti-seize. iirc the nickle anti-seize is good for up to 2200 deg.
on the brake lines, yeah those look a little on the crusty side! I would try your best to save on the line nuts, most likely they are metric thread. get you a roll of Ni-copper or whatever they call it now brake line that easily bends and wont rust and a flaring tool. on the line nuts, you might have to break off the lines so you can sue a 6 point socket and save them. if the steel line is rusted solid in them, use a drill bit the same size of the line to get them out so you can reuse them. drop all the line nuts in some acid or vinegar to desolve the rust. phosphoric acid will eat the rust in no time.
bleed the system as best you can with a helper, then you'll need to connect to the ECM to get air from the ABS pumps. That might mean a trip to the dealer or a shop that has the power bleeder equipment.
