Re: Nail Knot
Yes, absolutely you can tie your tippet on with two nail knots. It is the same as using two Uni knots. Two Uni Knots can be used when larger diameter mono is tied together. It does use up you leader as you change tippets.
The Surgeon's Knot is very simple and quick to tie. I don't like it because the knot does not lie straight and is bulky with heavier mono.
Like Peregrines suggested, I use a loop to loop connection to fasten the tippet on. It is the quickest way for me and very easy to change tippets. It also keeps you from cutting off any of the leader every time you tie on a tippet.