Hello @puremage111 !
1.You can cast only 1 vote per ARK account/adress. You can vote for 2 or all 51 active delegate by creating more ARK accounts and transferring your ARK to those accounts and vote from there.
2.No, you just need to vote once.
3.You need to remove you vote first and the you can cast you vote to another delegate.
4.Yes, It makes all the difference how much ark you got in the account you vote from.