Surprised your agent wasn't able to answer these questions for you, but here you go;
There are several websites that have pictures, just do a google search or you can go to the cruise line's website.
You are not allowed to take food off the ship - this is due to local laws about agricultural and meat products.
Yes, you can go back on the ship, have lunch, and then get back off the ship.
Unfortunately, after certain hours, usually around 1:00 - 2:00am, entertainment stops and there are only a few bars open and perhaps one or two 24-hour places to get food. Some ships will have the hot tubs and/or pools open, but all of this depends on the ship and the cruise line.