Here's one of my latest pages and quite literally everything but two points are done in Photoshop. The text bubbles (not the text itself) I ironically just use MS Paint. For me, it's easier getting a circle or oval done there then on Photoshop and I use Inkscape to resize the image. I think it helps with vectoring but that might just be me. Otherwise, everything else, from the lineart, to the line thickness, to the tones, shading, textures, text, layers, image mixing, backgrounds, everything is done in Photoshop using a mouse and a keyboard.
Using a mouse isn't so much practice as it is sensation and feeling. You need to get your hand used to your mouse, just as you need to it get use to your mouse pad and its frankly something that you never fully get used to. Every new day when I first get to drawing, I sometimes just have to move my hand around and get used to the feeling of my mouse and smooth my mouse pad out before I can get into the groove. However once I do, it's easy and simple and the feeling comes naturally.