okay so btc sending fees right now are very low if you choose low or medium priority.
It depends on the wallet you used, if you use closed source wallet or a wallet with bad fees estimator, they will charge more than it's needed. Moreover if you use exchange, don't surprised they charge above $10.
How do you check what was the low/medium/high sending fees previously like say hours earlier or week earlier. Can you check that with mempool or its always a current sending fee now?
You can check it on the mempool and click the specific time you wanted to see
https://jochen-hoenicke.de/queue/#BTC,24h,weight the fees isn't depends on the network alone. Addresses type, input, output, etc also the factors.
So if you were to send small amounts to someone... say 5 dollars or less, it makes sense to use BCH or LTC usually? Because even as low as the BTC sending fee is now... normally its bit higher?
Yeah, why not? (but I wouldn't hold scam coin e.g. BCH) however if you've learn LN network and done set up it, you can send Bitcoin with cheaper fees like LTC.