Question [Q] Help with development- Specfic

Hey all! I'm really sorry, I usually only lurk/look around this site, so I don't know if this is the right way to ask for stuff-

To be specific, i'm starting a company project (I run a non-profit organization) that helps people out around the world. I'm trying to change android OS to only do specific things (starting a specific app when you turn it on, etc). I want it to basically be stripped down to only do specific things. If someone wants to help out, can you point me to a place to understand how the OS structure is set up? I saw the programming page, but if it's no trouble, i'd like a little direction. If someone could PM me, that'd be cool, or respond here. I know most of you do this as a hobby, but a small payment for some direction wouldn't be out of the question.

I'm really sorry for the weird request, but i'm just starting this and thought i'd ask here first.