Hi, I am new here. A friend of mine said this is the place o go for help with wood, so here I am.

After much consideration I have decided to replace my old Formica countertops with wood countertops. I'm prepared do the work for upkeep but I'm not sure about a couple of things. I pan to purchase the countertops at Connecticut Wood Group in Enfield, CT. I'm thinking of rustic walnut for the countertops and maybe a live edge board for the breakfast bar. CWG will glue up the wood and my friend will install them. Some questions:

1. What is the best finish for this? John at CWG said an oil such as Watco but I read that ha varnish in it.

2. I was also told to top mount the sink but every picture I have seen so far has been undermount.

3. If I go with undermount, how should the end grain be sealed?

Thanks for the help!