1: How good do you want it to look. For best results it's back to bear wood, apply several coats of thinned varnish, rubbing down and cleaning between each coat.

IMO for best results use Epifanes varnish which I and many others thing is the best.
You should thin the first 4 or 5 coats 70% thinner 30 % varnish and then use 50/50 mix for a COUPLE OF COATS and a final coat or two of 40% thinner 60% VARNISH

that will give you the best result and a mirror like finish but it's a lot of work. You can cheat by using lesser quality products, applying fewer coats and using thicker varnish (ie less thinner) - it's up to you each of these will compromise the finish.

I have got a perfectly acceptable finish on a old Enterprise Dinghy using ‘Deks Olje’ by applying 2 coats of the oil and 3 coats of the gloss. This was done outside and produces a reasonable finish.

It depends on how much work you want to put into it.

2: See 1 above - surface needs to be anded and clean before you start then sanded lightly and cleaned between coats

3: Epifanes is the best but the most expensive. whatever you choose use a good quality 'yacht' varnish form international, Blakes, Jotun etc....

4: |If the boat I kept afloat for more than a few days at a time then you need to anti-foul her. Problem is you need a different type of antifoul paint inland than you do on the sea.

If the boat is kept out of the wter then there is no need to antifoul at all

Good luck - with wooden boats you spend a much time 'looking after them' as you do using them so you need to enjoy the maintenance...............