For short to mid term i think trx, dot and ada can prove to be profitable especially if you can hold for 6 or more months there are more coins but i feel these 3 are better and safer.
Yes, but other Altcoins are also safer for the short term such as Litecoin, XLm, and BNB, although BNB is also suitable for the long term, it can also be profitable for the short term apart from the three Altcoins you say.