I've done some plumbing repairs, water heater and furnace installs, but I may be about to install a bathroom from scratch. It's a concrete room that was used as a dog kennel. It has hot and cold and a 4" drain in the middle of the floor with its own septic. I want it to be 2 bedrooms and a full bath. What's the best way to get the toilet outlet to the drain? I suppose it needs to be vented, right? I see all kinds of mix and match plumbing these days...flexible hoses, PVC, shark bites...is it still as good to do good ol' copper and solder? Gladly accepting suggestions about any part of the process.