Hello Andy,
I'll be very pleased to answer to your questions. Let's start with these ones ;-)
I don't know exactly what kind of mahogany it is (I suppose african one), I bought a tree slice (as I love to call it): it was a piece of mahogany of 3m of length and 60cm of width. The finish is just oil: I didn't apply any other product on it a part on the fretboard that, due to the fact it is maple, it tends to become grey, I applied a couple of coats if sandind sealer.
On the mahogany I applied an oil that is a little redish and enhances the beatiful color of this wood. This is the link of the product I used: http://www.saratogasforza.com/ita/products...3-88BCD095D74F}
I suppose that you will not have any particular problem in finding a similar product: it is simply oil for mahogany.
The main advantage of this kind of finish is the sound: pure wood. I really love the sound of this guitar: full and warm.
Let me know if you have any other question.