Yes I use the Feast Watson reducer and as for ratio I have used anywhere from 10 parts reducer to 1 part stain up to equal parts reducer to stain depending on how dark or light I want the stain. I normally have a colour in mind and try and just play around a little bit until I get it as close as possible. I bought some syringes as it makes it really easy to get my ratio right. I have used a sanded piece of pine with sealer on it and mixed different ratios and applied small amounts on the wood and written the ratio near the area so I have a reference later on.

The cutting compound I use is what ever I can get from a Auto parts shop. I try and get straight cutting compound without wax in it. If it has wax in it it makes it hard to repair later on as you have to use something to remove the wax. This is helpful if you polish through the poly and stain, experience is a wonderful thing. I normally look for cutting compound as most cut and polish have some sort of wax. Ask at the store if the product has a wax in it just to be sure.

I have never used a cotton buff with rouge as I don't have the setup but I am looking to try it on one of the many guitars I am in the process of building to see which is better and easier. Some shapes would be a challenge to buff but you can get small round buffs for a small tight radius that I use in my drill. But seeing as I can vary the RPM on my drill I don't want to run it to quick and melt the poly, not sure I can do that with a cotton buff.