If I were in your position (and I have been) I would think long and hard about whether it's worth it to plan a future with your fiance at this time until he grows his own backbone. Do you really want to spend the indefinite future playing tug-of-war for your husband's time with a 'platonic' friend of his? Situations like this only get worse as time goes on, not better.
IMOP, your fiance should automatically know what is appropriate and what isn't. He shouldn't have to consult you to find out if it's okay to spend the night with his friend, or consult HER to determine YOUR (yours and his) holiday plans.
I hate to say this, but I was in a similar situation like this. My boyfriend asked me if it was okay to spend the entire night with a 'platonic' friend of his, too. Later I came to find out it wasn't so platonic after all. He was just asking my permission to test how gullible I was and how much he could get away with.
The fact that your fiance had to ask you about staying overnight with his friend indicates that at least on some level, he knows it is inappropriate. BTW, dinner and cuddling on the couch in front of a movie before staying all night - that's what people do on a romantic date.
The holiday gift giving issue is also raising a red flag for me. A platonic friend doesn't make demands about Christmas gifts - usually, they expect nothing, or at the most an inexpensive "friend" type gift - nothing more than $20 in value. A romantic girlfriend, on the other hand, would be in a position to be a little more "dictatorial" (for lack of a better term) about the type of gift per the level of seriousness of the relationship.
When I was in college, I had a good male friend who was very much like a sibling to me. At that age, we were ALL tight financially. At holiday and birthday time, the MOST we ever gave each other were cards with maybe a candy cane taped to it, or at the very maximum a $5 or $10 off card at a chain restaurant or record store. Nothing more was ever expected. Even when we got older and more financially stable, holiday and birthday gift giving was limited - holiday card, or birthday card and maybe take each other for dinner at a nice chain restaurant, or go as a group and all chip in to pay for the birthday guest's meal. Nobody agonized over gift giving. That's for serious romantic partners and spouses. (!)
OP, it sounds like you're not comfortable about any of this or you wouldn't have brought it up. Your intuition is trying to tell you something. I think you'd do well to listen to it.
If nothing else, don't make this relationship permanent until the 'platonic' friend of his is either in her rightful place....or out of the picture completely, and you're 100% comfortable with ALL of his relationships.
Take all the time you need until you genuinely feel ready, and until then, keep your options open. I wish you well.
**edited by mr kitty for additional content -- sorry**