For a laptop (or any other PC that uses a single input voltage) , AMD vs Intel really doesn't matter.
For desktop hardware it's a significant consideration, as Intel CPUS typically draw from 12v while AMD CPUs typically draw 5v. Because of this, an ATX-compatible PSU would need to provide sufficient amperage on the appropriate rail to power the CPU, as well as any other hardware (HDDs, USB devices, RAM, Audio, Network, etc.)
1. The Carnetix outputting 19v will do you well for powering the laptop.
2. Turning the laptop on/of w/ the Carnetix will be the most difficult portion of the build. This is the one piece of the puzzle that directs many people toward desktop hardware, as it's a lot easier to setup & configure.
3. Running w/ the lid closed is easy. There's a Windows setting that dictates what event takes place when the lid is closed. Set it to do nothing, so when you close the lid, the PC continues to operate normally.
As an aside, Kudos for getting the synapses firing and actually doing some research. Too many users here jump in and start asking "How do I do this?" when the question is answered already should they choose to take a look.
Thanks for being a refreshing change of pace!