Can’t help you with 1) (although my offhand guess is “yes”), but I can with 2) and 3)!!
First, let me say, I am answering only with respect to butter cakes (which both of yours are, of course)!
I ALWAYS freeze and refrigerate my cakes. I’ve never made a cake on the day I planned for it to be eaten, and I NEVER syrup them. NEVER. (Not that you CAN’T—I just don’t like syrup much, myself, and the cakes definitely don’t NEED syrup to be perfect after refrigeration.) Most get better after freezeing or being in the fridge a couple of days. It’s like the flavors—even of “plain” cakes—and textures all equalize. Once again, I think you CAN syrup if you want to, but I would say it’s not at all NECESSARY.
You can wrap the layers in plastic wrap and refrigerate them, then frost whenever. Or, you can compose the entire cake and refrigerate it until the frosting is solid. You’ll want it covered, of course, but since it’s a wedding cake, I’m not sure how that’s done. For “regular” cakes, I frost them in their carrier, refrigerate until the frosting is good and solid and then “cozy” it with plastic wrap, trapping some between the carrier top and bottom all the way around. Not sure what a wedding cake is “stored” in.
If I’m going to freeze, I freeze it until it’s really frozen—it can take some good abuse then—and then wrap it tightly in plastic wrap and then foil. Then, to thaw, I remove the foil and plastic wrap, put it in the carrier, “cozy” and “cozy” it with plastic wrap.
When you go to bring it to room temp, take the plastic wrap off first, because you don’t want to mess with plastic wrap on a room temp frosting!!!!!
Good luck! Can’t wait to hear about your cake!