Re: the apartment, different landlords have different approaches. When the boyfriend and I were looking, most around here wanted either a dual application or two separate applications - essentially, the same as if you were renting with a roommate and both of you were going on the lease. Some made it clear that they required one person to meet the income/credit requirement by themselves, I guess to make sure the lease was covered in the event that we broke up. I'd take it on a case-by-case basis, it may depend on your area and the type of landlord you're working with.
This is not relationship advice, so much as general financial advice: I'd avoid sharing a car loan with anyone, or at least have a very clear Plan B if things don't work out. Car debt is a hassle to settle if the relationship goes south, even if both partners are trustworthy. Could one of you afford to take on the financing alone? Regardless of the relationship length/trust/etc., I think it's good financial policy to have a plan in place that you've both agreed to.
As far as getting the loan, if you choose to do so, you could head to a bank and have them run it a few ways: you alone, him alone, and together. When I (briefly) sold cars, most unmarried couples who came in had the person with the highest credit put the car and loan in their name alone. But since it sounds like there might be a large income differential, I think it's worth actually sitting down with someone and running the numbers if you choose to go that route. Also, some financers had requirements that the "primary driver" had to be on the loan - I don't know how common that is, but that's something to keep in mind if one of you will be driving it a lot more than the other.