Sewer being involved, I shudder at the likelihood that this is done up to code.
I know I sound like a frigging idiot, but truly I'm not, or truly I intend on doing a good job. As I mentioned earlier, I built a passive solar adobe house back in the '80's, and I did all the plumbing, both septic system and household, and I did a good job and everything worked. It's just been a long time, and when I started thinking about this project, it was like I couldn't remember a darn thing. But once I stood in front of the bins of plumbing stuff at the supply store, I felt like it was coming back - of course its a wye. But I still need some serious refresher work from some books and advice from places like this - and I'll get them.
One thing I've noticed - if you want to gain a deep appreciation of almost any trade, try doing it yourself. I make most of my living as a recording engineer, and I often work on projects that people started at home, as home recording gear is very easy to come by. But then people often wonder, "Why does my music sound like you know what?" And then they either spend a lot of time figuring out what to do to make it sound better, or take it to someone who's been doing it for 30 years that can help them.
And so it is with so many things - I'd love to hire someone to do this who really knows what they are doing, but I'm at the tail end of a new recording studio building project, and the bucks are a little hard to come by, so here I am, gaining a fuller appreciation for plumbers!
But anyway, thanks so much for your input and help - I may post back here with some q's about interior plumbing soon, if you all can put up with more stupid questions. But I also believe that, for me, the only thing more stupid than a stupid question is not asking it. Thanks again for the help, and all best to all!