#3
I was going to say the same thing. Be really good and post a link to your video on U-G. People will check it out and comment. Also, you can place an audio copy of the music on your profile page. People will play it when they check out your profile.
#6
Find good ways to get people to your channel.
Lessons on techniques or songs.
Covers on songs.
Good sound on your recordings.
The more interesting/impressive your videos are, the more they are going to be passed on.

And yeah, put a link in your profile, or even signature.
I've clicked a few Sig Links.
On playing the Paul Gilbert signature at the guitar store extensively, my missus sighed:
"Put it down now, It's like you love that guitar more than me!"
In Which I replied.
"Well it has got two F-Holes!"