Hello Mr. Tom, I'm rehabbing a house from beginning to end. Everything is gutted out walls, plumbing and all.. I have a Stink stack and just cold water lines ran. How and where do I begin on running all new plumbing for my house.. Approx how hard would it be and what would it cost? I consider myself a very handy woman and follow directions well.. As I look at existing houses plumbing it doesn't look too complicated but me being a newbie I'm sure it will. Just please help on where to start.. I was thinking starting with running pipes to the stack for the toilet.. I have 1 bath but another room right above it where I could possibly run pipes also for a second bath.. Thanks>> DIY-Lady

I don't know who Mr Tom is, but you do sound like me when I was young. Ripping everything out before knowing how to put it back together. That's when your husband or signif other packs up and leaves you.
Copper is expensive at the moment so everyone is using Pex. The crimping tool is expensive and some of the fittings. Or you can use copper and learn how to solder by filling the first few with so much solder that you flux way too much down the pipes, and a pipe leaks anyway because you tightened the pipe cutter too much on each turn and dented an edge.
Sure, start at the toilet. It's nice to have one if you're living there.
It's a lot more convenient though it you map out the whole house so you can shop for all those valves, tees, elbows, etc at one time.
You are the only one who will know how much it will cost. Draw it, make a list, add up the prices. Then add some more because you'll forget something.

It may be a bit complicated for somebody who has never done plumbing before. Also, some specific tools will be needed to accomplish the remodel. Any way you could post drawing of your house and bathrooms ? Also show the stack a direction existing drain goes. Back to you. Milo