Should I ask both in one question-post, or create two separate ones? And what if I already asked a question and another question comes to mind, also somewhat related, but its to late to edit the original question since it was already answered? I always feel bad for "spamming" two questions, so most of the time I end up asking only the more important one, wait a day or two, and then ask the other one.
Ask well and ask often!
If you are writing coherent sensible questions then I see no issue with posting them within minutes of each other.
This becomes problematic to the community when the quality of the questions is poor, or the asker shows no sign of learning or understanding and can't show any insight. Steer clear of that and you'll be fine.
For what it's worth, I've asked > 100 questions and our most prolific question asker is a Stack Exchange employee. So go for it.
Ask by all means but in addition to what Mark said, bear in mind that if the questions appear to be too closely related one may get closed as a duplicate of the other. We sometimes interpret "identical" very loosely.