Hi Mouthy One,
I'm sorry to hear about your surgery, you are in the right place for support.
With eating, it's like your mouth has gone back to being a toddlers mouth. You need to slowly introduce small bits of soft food at a time. My first 'meal' was a spoonful of mashed potato with a lot of gravy. It took me over 30 minutes to consume.
13 months on I'm not doing too badly with food, it just takes time and practise. At the moment your mouth is full of stitches and will still be swollen in places, so you've got to take it easy. You've been through a lot.
Answer to your questions:

1) It's up to you with how much you try, how long it takes you to recover, and how patient you are. Give yourself a break with trying to eat solid foods every so often. It's exhausting trying to eat solid foods. Extra sauces and drinks help, but smaller mouthfuls work much better too. You need to re-train your brain and mouth to find a way to eat that's comfortable to you.

2) The slobbering and spitting is your mouths way of protecting itself after trauma. It does ease over time, it just depends on each person on how long it takes.

3) Those stitches are annoying aren't they! I think mine finally disappeared after 10 weeks, but I can't remember exactly.

Get on the phone to your doctor and talk about the blisters. We're not professionals, we're just like you. Get yourself checked out for your own peace of mind .Even suggest having a meeting via zoom/video call, if you're able to show the blisters on there.