1. Be sure that you are using an authentic electrum wallet downloaded from electrum.org and verify the wallet.
Check, did this.  Have my phrase recorded on paper.
Not sure how to download the signature file.  When I double click, it opens in HTML.  Should I save this as a .txt?
https://electrum.org/#download
2. When you copy receive address, have a cross check that the address is the one from your wallet because there's a malware which can change your copied address.
Which exchange is recommended for US citizens?

Also, what is KYC?

Noob here.  Trying to figure out my first transaction.
Let's say I want to move $1k from my bank account into bitcoin.  How do I go about making this happen?