Re: Need some advice on first build..
You would be surprised at how much you need to know about bicycles before building one from frame up. I did that once and got super confused when I found out that not all seat posts, forks, head tubes, cranks, etc (you get the idea) are made the same. I thought I'd just buy a junk bike and use all its parts, transfer them over to a nice GT2A frame and be done. $600 and several donor bikes later, I had the bike I wanted. And I'm a very experienced auto mechanic, and now work in the nuclear power field, so I have a very heavy engineering background. Yeah, it would be easy now, but that's because I've been down that road. So it's not impossible, but for a first build I'd recommend starting with a pre-assembled bike and kit, work out the kinks, then maybe try a custom frame when you're ready.
Never stop wrenching