Are there any problems with an inside guarantee room? I don't mind not having a window, but is there anything else bad about them? Is it true that I will have to carry my luggage the whole time during check? Also, how many pools does the constellation have? I read there are some in the aquaspa, are they free to use? Thanks!
You will just have to carry your carry-on luggage through embarkment. Once you arrive at the pier, just turn over your checked luggage to the porter there, tip him a few dollars per bag and they will deliver it to your cabin.
As for you cabin, the closer you are to mid-ship, the less moving you'll feel, other than that, there should be no difference between any inside cabin, just location.
The aqua spa pool is no charge and is inside, great way to relax, we loved it on Infinity. I do remember there being at least two other pools and a few hot tubs as well.