yes
A small flywheel needs to stay with the starter that goes to it. You can use either flywheel, and the block should be drilled for either starter.
you need a 350 put the 305 in the junk yard How long has the 305 lasted? Is it strong enough for you? If you need/want more power, go for a 350. If it's going to get extreme service (racing, heavy hauling), you might need the 4 bolt main, but probably not if it's just normal driving.
nothing is wrong with having a 305 but if you want build it up for more power the 350 w/4 bolt mains is the better option if its for daily driving use the 305 its should be better on fuel
no
yes
No way. NOT POSSIBLE NOT EVEN CLOSE
yes
yes
YES. They will bolt right up.
Yes it will bolt right up, no problem. As long as the 350 is close to the same year as the 305.
Yes, it is the same bolt pattern.