First of all welcome and congratulations on officially being part of this forum!
The crypto world is vast and wide so do not be frustrated if it takes you quite a long time to learn or understand something. It took me a while too but this forum helped so you are in luck.
I assume I own $200 or whatever the 0.00% it is off etherium. Is this correct?
Yes. Whatever the price at the time you bought it would be the equivalent amount of ethereum you own. For example if you buy a coin pricing at $10 and you have $50 then now you have 5 coins. This will change as price goes up or down.
1. Do i do the same and open various wallets and buy the coins that way or do I have to use an exchange like Coinbase or Binance to buy the coins?
You do not have to own multiple wallets for each coin. You can just have one wallet that holds all of your coins. And no, you do not need to use a centralized exchange such as binance or coinbase. There are lots of different kinds of wallets and exchanges. You need to determine which one would be well suited for you and your needs.
I am really sorry if these are basic questions for you but I fell my knowledge is very very limited weak in Crypto, the more I read on this forum the more confused i'm getting. I would like to buy and hold the coins long term but would also like to sell short term if I don't feel i have chosen the correct coin/s.
never feel bad for asking questions. we are all learning here and it is great that you have done the initiative to learn. I wish you all the success in your crypto journey!