1. Not easily
2. Not easily,
3 on swapping the gearset, Plain Old NO..You can't swap in a "T/A" set for only one gear as the cluster gear needs to be of the same teeth count..Kinda like trying to run a 4.30 pinion on a 3.55 ring gear...As a rule of thumb, the only way to swap gears around is swap the entire internals from case to case.
"E-body" 4 speeds are nothing "Rare"..All you need is a B-Body 4-speed from 1970-'74 and it will have the mounts for either car on the tail shaft...You REALLY need to try and get the proper trans..A-body is usually considered to be all by itself...You might even get lucky and crawl under say a mid 80's Dodge truck and find the O)'D trans that WILL bolt into your car, but will still have the 3.09 first gear..