mempool.space is one of the best places to find out what fee you want to set.

Note that if you set the fee too low, the transaction will most likely just take longer (days, weeks, or months).

The worst case is that the transaction never confirms and the network forgets about the transaction eventually.

Fortunately, until you see the transaction confirmed in a block, you can assume it is still in your wallet. Once confirmed, it has moved. There is no limbo really, and you never lose funds.