For #2, it depends on the mod.
I think the vanilla game will run ok at 1080, max settings on (non-gaming) laptops with modern quad-core's CPU's and discrete GPU's - remember GP4 vanilla uses CPU more that GPU.
But there will be some mods - and I think the 1991 mod is one of them - that can be more demanding on GPU as the detail level of cars (number of polygons) and tracks is what taxes GPU's.
I have a desktop with i7 4770 @3.4GHz, 32 RAM and a GTX 1060 6GB and believe me I can bring that hardware to its knees with crazy ultra settings in some mods (the CPU usage can get above 180% on starts). But with "normal" ultra settings, I will see the CPU going up to 60% max. By ultra settings I mean doing some unnecessarily manual modifications to the f1graphics.cgf above of max settings.