Not to rain on your parade, but if you haven't done any of the jobs involved (framing, electric, insulation) in a complete bathroom build, you really shouldn't try to take it on yourself. Granted, plumbing is probably the biggest part, and that you're hiring out, but still, there are loads of requirements for electric, fire blocking issues with the framing and insulation, heating requirements, etc. that will snag you along the way. The amount of mistakes you'll make, time you'll spend and the amount of fights you'll likely get in with your husband will make it ultimately not worth it to try to do yourself in my opinion.
First, there are many permits you'll need, which means many inspections, which means things will all have to get done and approved in a certain order before moving on to the next step. And since you are admittedly a novice, the inspector will rightfully be extra tough on you to make sure everything is correct. In many towns, it takes a while to get an inspection lined up (at least days, if not a week plus), and you'll need multiple inspections. You will presumably fail at least one inspection, which means everything gets delayed until you fix the problem, have him/her come back out, sign off, etc.
You'll need an electric permit, a plumbing permit (which the plumber might do for you, but not necessarily...the homeowner is always responsible for ultimately making sure all permits are properly filed and signed off on) and a building permit. You'll need to submit detailed drawings showing the layout of the room, all plumbing and electric fixtures, framing and fire blocking. I even had an electrical inspector make me list in full detail what type and size of wire I was using, how many inches off the floor/countertop my outlet boxes were going to be, where I was going to put wire staples, calculate box fill based on how many wires I'd have in each outlet and junction box, etc. Basically, he wanted to see that I knew every single part of NEC that pertained to my job. And he checked it all those details too when he inspected.
So you'll need to reseach in detail every code and planning issue before you apply for permits. Then once work is started, you'll have to have the following inspections at a minimum: framing, plumbing rough-in, electrical rough-in, insulation, final plumbing, final electric, and I'm honestly not sure where HVAC falls in...presumably plumbing as well depending on your type of heating system. If you fail along the way at any of these, you need to redo the work, have the inspector come back out, approve, and then you can proceed with the next job.
Next to completely gutting and redoing a kitchen, or adding an addition, adding a basement bathroom is arguably the biggest home improvement job there is and therefore is best left to a pro, or at least a VERY experienced DIY'er.
I am a self taught DIY'er (lots of books, TV and hands on experience) and consider myself very seasoned at this point. I've done complete bath and kitchen redos in my own homes and I know what all is involved and the snags that inevitably pop up along the way. Unless you are extremely confident in your skills and abilities, you should reconsider doing your project yourself.
Again, I'm not trying to hate on your idea (as much as it sounds like I am), and I apologize. I fully encourage DIY projects because of the sense of pride, accomplishment and potential cost savings they bring. But the best advice I can give based on my own experiences is to know your limitations. A complete bathroom job is not the job you want to use to get your feet wet.
Yes, we are complete naive bookworm novices. After receiving all your warnings, we've decided to go with a contractor. I think it will end up costing us about 2-3k more, but we'll definitely hang around and get our hands dirty so we can learn from it.
