For your first problem, stuck bolts, there are many threads on that, even in by me on taping, but the main thing you need is patience and heat. I use a mapp torch. For this issue, heat the bracket up by the bolt. Not red, just maybe 10 - 20 seconds ( i think the bracked is aluminum ). Then I spray pb blaster on the BOLT ( heat seems to suck it in the threads ) and then gently try to loosen. A little at a time is all you are looking for.
Do the non broken one first.
When that one is loose, work on the broken one. Get a vise grip in there as close to the transom as possible, and using the same paitent technique, loosen it only enough to remove the motor from the transom.