Wow Sabreuse it does sound like there's a lot of stuff to work out, maybe if you break it down it will be easier to deal with, one question at a time?
Getting around - if that's an issue it will make you very isolated, as you say you can't go to tot groups but I'd imagine that means going anywhere is a problem. Is there anywhere you could get a double buggy, even temporarily? Or second hand as I'd imagine they hold their value. I appreciate this still needs a cooperative 3 year old, my 2.5yo DD will hold onto her sister's pram and walk for 10 mins quite nicely, otherwise 1 and 3yo could go in the double pram and youngest in a sling for the short walk eg from car?
Dinner time - would the 1yo go in a baby bouncer/baby walker while you prepare food? Think at 1yo my eldest loved playing with all the food tins, spreading them around the kitchen or putting them into cupboards. 3yo could help fetch things/pretend to cook with you, or just watch the telly? I also started using a slow cooker after reading a few threads on here, it's such a help on a difficult day.
Sorry if this is all rubbish. If we can't offer helpful suggestions and you just want to vent, please do that, and we can listen!
And regarding feeding - it's really about what you want to do, if you actually want to bottle feed then go for it and that's the end of the matter, if you want to bf then there's no reason why you can't, as presumably there won't necessarily be someone there to help bottle feed, in which case you've just created more work for yourself (essentially what Bundaberg said).
FWIW my mother had us 3 close together, it was very hard work for her when we were babies but my sisters and I all appreciate the closeness we have as a result - so it'll all be worth it in the end!