For these types of landing pages, does domain name matter?
Do I have to register a domain name related to the niche/offer, or can I just use one and host different landing pages on that?
you want to avoid using domains that are super keyword rich for CPV, because people will bid on a phrase like auto insurance deals or autoinsurancedeals,
and you would be popped on if your domain was superautoinsurancedeals.com
I try to go super generic, like deals4theday.com - promotionaltracker.com
In the tests I've done the answer to this is "depends." Sometimes it has increased conversions for me, sometimes it does not.
If you do a test on a campaign and are coming close to breakeven, one of the variables that are very easy (and cheap) to test is just changing the domain. I've seen as high as a 10% increase in conversions on longform lead gen campaigns I've run, and I imagine if you're doing something like a shortform email submit it can be even more drastic.
i used a generic domain with high converting offer that lasted for a 2 years.
for me, the offer is more important then the domain where the lander is on.
you can check tijn's thread Protect your Nuts, will get more info what you want.
In my tests the domain names makes more difference in pop-unders that in pop-ups. But, like everything else you should test it, especially if you're going to be sending a lot of traffic.