To answer your questions:
1. I use a swivel knife to cut the top grain for tooling. To cut leather pieces for a project, I use a knife I made but many pards use a head knife, an exacto knife, or any other type of good sharp knife. The first photo below is of the three knives I use the most. The top two are made from a power hacksaw blade.
2. I prefer Lincoln leather dye for color and a good saddle soap after it's dry. If the piece needs to be softer and more pliable, I'll put on a light coat of neetsfoot oil.
3. I don't usually dye leather when it's wet. I have dyed it wet if when I didn't want the cye to penetrate as much.
4. When tooling, I usually use a tapered blade in my swivel knife for tight radiuses and a flat, double-sided one for straighter lines. I also have one that has 4 cuting edges for making a texture like grass. The second photo below is of my three most used swivel knife blades. The one on the right is the one for making crass cuts.
5. Any cutting board works fine although I like a large, heavy one best. My favorite is a large piece of butcher block that won't shift when I cut.
I'm sure others here will add their ideas and techniques to this so keep checking in.