Congratulations! Your first cruise and your new marriage -- hope they both are terrific!!!
The embarkation process can be a little tedious, but be patient it is worth it. Show up as early as your paperwork says to -- provided you don't mind standing in long lines. Me -- I'd rather be at the front of the long line that at the end so I show up real early. Be sure to fill everything out they send you ahead of time and be sure to look at both sides of the paperwork. BE SURE TO HAVE A PASSPORT OR Certified copy BIRTH CERTIFICATE even if you are both US Citizens!!
Your travel agent may be able to contact the cruise line and get your cabin assignment, but if not don't be disappointed if you don't get an upgrade. Depending on how full the ship is it may just not be available. If you HATE the location of your cabin (e.g. next door to the laundry) they might be able to move you if the ship isn't full. But except for your private rock n roll parties, you won't be in your cabins much and when you are you won't really be noticing the furniture will you??
Buy the photos -- at least the embarkation and one formal night -- you will be glad you did even if the price feels like a con.
My advice -- controversial as it may be - is do the ships' shore excursions, unless you are REALLY confident and experienced travellers AND speak Spanish. The ship's excursions cost more, but here's the MOST IMPORTANT THING TO KNOW -- if you are on a SHIP-sponsored shore excursion **THE BOAT WILL WAIT FOR YOU ***** -- if you aren't and you breakdown, get lost, or whatever -- it won't!!! No lie, it happens almost every cruise somebody gets left behind because they didn't get back when they were supposed to!!
Have a great time!