You can name site names but can't put it in the "URL" option, just as long its not like this Ex:"Hey come join my site scambux and get $0.03 a click!" just as long its a conversation about where you advertise or just mention a site.
Yes thats one way to get referral is to advertise on other sites but it may be a little hard to get referrals because a lot of people know about ClixSense.
Install the toolbar so you can be more likely to get ads, referral people to increase your earnings, upgrade your account to Premium to earn more daily.
It mainly depends on the user that signed up, I got a couple from neo and most are active but if your going to advertise there do a big amount of clicks because Clixsense is heavily promoted over there. The one direct referral I got from there bought something (I guest advertising) and last click was the 16th of this month.