I am not yet an Oxford student but received an offer from New College after applying there. I am also in a similar situation with income. The money you get from Oxford will be in the form of the Oxford bursary, which doesn't depend on the college. Most other scholarships and bursaries are also university-wide, but you can check on the Oxford website just to make sure.
My college (New college) will have accomodation for all years (currently they are building the 3rd year accomodation building but it will be done by the time you get to 3rd year). Most of the rooms are en suite, but accomodation is randomly assigned so you may not get an en-suite. I would advise that whatever college you apply to, contact them and let them know that you would prefer an en-suite for religious reasons. They will probably be able to accommodate you, as long as they have en-suites.
Other than that, keep in mind you may not get into the college you apply for, and also take into account other factors. For example New college has quite a lot of students, is one of the oldest colleges (ironically) and has old buildings, and is also fairly close to the city centre. You may also want to check how many tutors they have for your subject and if they have any that you would be interested in learning from (e.g. if you know any books or papers written by tutors at Oxford and would be interested in talking to them).
Good luck with your application!