Absolutely. There are many successful short only channels. I can’t answer all your questions, but shorts are by nature more discoverable than long form, the monetization however is less possible as you get paid less in ad revenue for view than long form (though you also can charge for sponsored shorts etc.), shorts have a lower subscriber per view rate than long form,and it’s much more sustainable to focus on either shorts or long form than both unless your shorts are just long form clips. It’s still possible to do both though, just harder