Re: Questions about Warmoth custom
You just have to decide what is most important to you-- the burst finish, the opportunity to customize, the bonding experience with your grandfather, or money.
For me the most important things would be the experience of building something with my grandpa and money (I don't have much). So for me personally, I'd build the Carvin kit and apply a burst finish myself. (It can indeed be done by amateurs, check reranch and projectguitar.)
But your priorities are your own. You're leaning towards a Warmoth build, and like we've said, not a bad way to go!