This is a really good resource on Game Boy modding and repair..
For my own Color I went with the Hispeedido/OneChip OLED kit. I'm happy with it. I recommend using NiMH rechargeable batteries with it. I get around 5 to 6 hours on two Eneloop Pro AA batteries.
Obligatory picture of the Boy.

As for the Pocket, you're probably going to have to cannibalize the part from another unit. I did a quick search on eBay and did see a few working LCDs for around $50 each. That isn't really a good price since it's possible to find a functional Pocket for around the same price. Though, it can be difficult to find one without screen cancer these days.
I'm my mom's go-to person for assembly. I'm generally okay with it. It's worth noting that I build gunpla for fun, so it makes sense to have me be the one to do it. Though, I can't really say that I enjoy building the furniture. The frequent use of Allen keys certainly isn't helping the furniture's case.