I will add just a couple of things. A grinder is probably your best bet and will make a valuable addition to your tool collection. You can keep a stone on one end and a buffing wheel on the other, at least that is how I do it. I keep a number of buffs on hand for different purposes. ALWAYS use the spiral sewn buffs. The buffer is the most dangerous tool you are likely to use. BE CAREFUL!
You will need to use separate buffs for each type of compound to avoid contamination. Keep them in plastic bags when not in use. Zip-lock freezer bags work great. For cutting, which means getting out the scratches, you will need a green rouge. I prefer Osborne Stainless compound. It is the most agressive and fastest I have used. For a light cut get a white rouge, such as Foredom, handled by most hardware stores. For final polishing you will need a red. I use separate buffs for things like carnauba wax or beeswax, which are nice for finishing handles.
You must get all of the scratches out of the blade before buffing to get a quality finish, hence, Bob's Bookcase. I rarely mirror polish anymore, but when I do, I find that I can do it from 600 grit as long as I have done a good job on the hand finish stage. The blade must be carefully cleaned between each compound.