Shape and size will depend on what you are cutting for a subject and how you want that subject portrayed in the end. Ie flat, rounded, deep cut, shallow bas relief, etc.
As far as shapes the traditional ones you may need - 90 110 120 - I have carved complete coins with a 120. You can cut the outlines and lay it over on its side to shave with.
Flats work just as well. You can do the outlining and shaping. I would suggest you radius heel your flats a bit so they dont dig in and you can come in at a higher angle.
Any size from about 1mm to 1/8th inch. If you need the gravers to do something differnt use them upside down (seriously)
I love the GRS QC's and for the big boys i regrind mullers
In general the smaller the better.
that should be enough to get you started, i'll try and put up some pictures of my coin bench/mess so you can see how it comes together.
Dont be afraid to think outsidethe box when cutting coins. There are no hard fast rules period. What ever works you do. Some where on this forum are some pic's of S.Adams tools. Take a look at the gadgets. There comes a point where much of this stuff is done without power when detailing and scraping. the it becomes a matter of sharp pieces of steel in the shape you need to make the curvature you want. That can be accomplished by pushing or pulling.
i'm a rank, i mean double rank beginner. flats #42 down to very very narrow ones made by yourself. i've made a few good flats out of ground down sabre saw blades. grind the teeth off and grind down to the thickness you want and you're in business. old dental burs are great pieces of steel to use. they are reasonably hard an are already small to start with. it does take some getting used to shaping these little buggers. you have to learn to use very gentle pressure or "touches" when shaping these little buggers. just a tad too much pressure in grinding these to shape, and you lose the entire point.once you start doing this, there's no going back. it's like jumping from an airplane. if you want to see the few tools i've made, and how i did them, e-mail me monk45@verizon.net. i cant teach you a heck of a lot, but i can at least give you a good head start on doin your own custom tools.
Most of us coin carvers have our favorite tools and i don,t quess there is any right or wrong tools, if what we use works for us, i use a flat #36 & #42 hand push gravers [ no heel] 50% of the time and my gravermax the other 50%..The gravers i use on my gravermax are a #36 flat[ with heel] and a 100 degree v graver..There are times when i carve a coin almost 100% with my hand push gravers and then again there are times i carve a coin almost 100% with my gravermax, but most of the time it,s a combination of hand push gravers and gravermax....