This depends entirely on your individual agreement/contract, you will keep gaining revenue as long as the agreement runs (so basically as long as you and tapas are in an agreement that allows them to showcase and sell that comic. Soooo as long as it's on the app, to my understanding.) If you and tapas both wish to renew the agreement towards the end of its period, it will keep giving you revenue as long as the renewed agreement runs.
Revenue depends on sales, so if you finish your comic long before the agreement runs out and then say a year after you finish it noone buys it anymore, then you will get no revenue anymore simply because there's no revenue that your series has gained.
I have no input on this, only observations. Some comics do go on hiatus when a season runs out, preparing for the next season. I've also heard whispers from other creators and readers that at least one premium comic was taken off because the creator couldn't keep it going. Obviously if you long term find yourself unable to provide your end of the deal, that will be cause for the contract to be ceased for both parties' sake.
The update rate can be discussed with your tapas contact if you ever find that you aren't able to provide updates as fast as before. I have changed the update rate on mine a couple times; Once I upped it to twice a week, and then this year i lowered it back to once a week. I do believe the preferred rate is at least once a week though to keep your comic fresh in the readers' minds.
Not really. Obviously if your comic gets very popular that means it is more likely to attract more good deals along the lines. And more unlocks sold = more money for you. So there are things to be gained in better stats, but not really any punishments for bad stats.
My suggestion is to have both. If you are able, it's good to have some free content that is NOT tied to your premium comic (for obvious reasons, things that belong to your premium comic should remain within the bounds of the contract unless there are exceptions agreed upon between you and tapas) running on the side with extensions of that free content (early access, special illustrations) available on Patreon. This will give readers a chance to ease into your content before deciding to invest in you whether that be in your premium comic or your patreon.