one thing I'm not sure is the "address" that ready filled up underneath where i key in my private
key, is it my electrum wallet address?
Yes. I assume you've backed up your seeds as well?
second, should i choose ETA as a fees?
If you don't want to spend so much on fees, you can probably use mempool, adjust to 1vMB or more and expect a confirmation within a reasonable period of time as well. You won't overpay for your fees this way but it doesn't guarantee a confirmation within X blocks like what ETA does.
The fees are reasonable right now, so the option is entirely up to you. As long as the transaction is replaceable, you can bump the fee in the future.