You didn't mention your computer's specifications. It's highly recommended to have a dedicated graphics card. GTX 950 , newer equivalent Nvidia or AMD card would do depending on the desired settings. ReShade acts as an overlay meaning it sits on top of the UI + game. Use the tools built-in hotkey for screenshots or another program like Fraps to capture screenshots.
You might be surprised not all of us use it. ReShade has gotten more optimized and stable over time. In my experience, you can still experience drops in framerate even with an overkill PC. We're talking 5-10 frames or more/less depending on certain circumstances. It bugs me enough to just use Photoshop instead. Others are not so bothered by it so it just depends on what settings you're using, PC hardware, and if you even care to track FPS like I do.