Hi Chris. Welcome to the forum! Boy, you are starting out with a bang, aren't you! That is one whale of an undertaking. It's fun, but let me tell you, you can burn out really fast on those teeny-tiny parts. I've been working off and on on this model for over a year (Real life: 98%; Model time: 2%). I started a build log but I've done so little the guys probably think I'm either dead or have given up. I may be slow, but I;m enjoying it.
Now, you ask about some parts. Based on the description and the numbers you gave, I'm assuming you're referring to the Pontos detail set. And yes, you are right. They are hatches and watertight bulkheads, if you want to use them. If you plan on leaving the plastic formed ones as is, you probably won't want to use these, but a lot of us plan on removing the cast ones and using brass. Also, some of us plan on opening up some of the bulkheads and if you do that, you will need to glue these onto both sides of a piece of Evergreen strip to simulate open "doors". There's all sorts of options for you, and you can do as little or as much as your heart desires. It's your boat and you can do whatever you want - as long as you have fun!
If this is your first big ship, you might want to make it more "generic" until you get some experience. There's absolutely nothing wrong with that! Kelly Quirk make an absolutely fantastic model of this kit using some of the more important parts of the Pontos set and a lot of Out-Of-The-Box parts. Check out his build log here:
viewtopic.php?f=59&t=155426I hope I helped a bit, and if you have more questions, don't be afraid to ask. We're a pretty friendly bunch around here and you can learn a lot. And, if you would care to, why not start a build log so the rest of us can see hoe you are coming. Unless you're like me, that is, and spend so little time building that folks get tired of waiting for updates and move on to other things.