It might be more useful to ask about specific models. Gaming laptops work well, as they have the right sort of spec, and have that economy of scale thing going for them. I like to use eBay to home in on a short list because of its filters. You can specify CPU, how much memory, make etc. and get down to a manageable short list of different models, and concentrate further research on that.
PC Laptops & Netbooks | eBay
To answer your firs question, you can't go wrong with Nvidia GPU when it comes to Photoshop. Issues can arise with laptops which switch between onboard Intel HD graphics, to more powerful GPUs when needed. This is to keep battery use down, but you can force the laptop to use the more powerful GPU when plugged in to main power.