Congrats on the bus... We want pics...
Not sure about the ins in CA, but there is a thread on here about the different state requirements...
The other stuff however, just take your time and read through other peoples build threads that interest you and what you would like to accomplish... There's a lot of info regarding tech type stuff... The plumbing can be salvaged from an RV like a motorhome or camp trailer...
The hardest part of your conversion will be convincing yourself that you can do it... Start out with some easy tasks, research and follow what you've seen others do... If you get stuck, ask for help...
It's gonna be exciting... This can be as fun as you want it to be, or not...
Good luck,
Luey...