For rusty bolts, a lot of penetrating oil and the biggest baddest breaker bar you can find (since most u-pull yards don't allow torches). As for the springs, until you disconnect the control arm from the spring seat, it can't drop low enough to release the spring, regardless of the shock being there or not. But yes use a jack under the spring seat when you disconnect that bolt.
Somewhere there's a DC10 struggling to get off the ground. I'm not a fan of wings on street cars, I like low key spoilers, but not something that you have to custom order from Boeing.