Hmmm interim answer hoping that an undergrad saunters by and gives something more definite!
The only en-suites that I have heard of are in Anne's Court, so realistically, no you aren't going to see much of en-suites at Selwyn. From what I've seen around College, and that isn't everything by a long shot, showers are shared between 2-4 and loos between 6-8 (3 cubicles).
Basic, again as far as I've seen is two electric rings (feeble) and sometimes a microwave (not from college, but because someone got permission to keep one in a kitchen). Rice cookers, grills etc are not allowed, but there seem to be a suspicious number of boxes of them in my nearest kitchen! Toasters and kettles/coffee machines seem to be allowed in rooms, fridges aren't allowed (all unless there are extenuating circumstances). There is a fridge in each kitchen though.
I mostly self cater, but last time I went to Hall there seemed to be more than one veggie option, not least because there is always a salad bar as well as hot options (plus sandwiches, home-made cakes, soft and alcoholic drinks, breakfast cereals, chocolate bars,fruit and ice-creams!)