Keep a small amount of BNB

Sometimes I accidently use all my BNB on a transaction. Then I am unable to perform transactions and its a hussle get BNB on the wallet again. Therefore I thought of 3 options:

1. To be able to use the coin that I want to sell for transaction costs instead of BNB. Optional is to cap this amount at USD 5 a day.
2. Get a warning if I want to use all my BNB on the Exchange and Liquidity page.
3. To be able to watch a few adds to get me a free transaction so that I can convert a coin to BNB