Is the baker required to provide service in either of these situations? Both?
I don't think any baker should be forced to provide service to anyone as a matter of civil law.
But you say that this is a Christian baker. What kind of Christian would refuse a customer's business just because the customer is gay? The central tenets of Christianity are about mercy and love (see for example Matthew chapter 22, verses starting at 36). If the baker in question is an observant Christian, he or she would probably be happy to bake the cake, so the question is a paradox.