I have a few questions before i sign up. Right now I have google adsense running on my site. Should I remove them before I apply for YPN?
Nope, I have seen lot of people who got YPN eventhough they had adsense on webpage. its all depends to you. if you dont loss too much revenue on that site, then i suggest to remove for a while..if site is big, leave ads as it is. NiL
You don't need to remove your adsense ads. I applied for YPN when I had a bunch of adsense ads running on my site. They approve it nonetheless.
To join? You apply first and if you get accepted your in. Only YPN would know the answer to that question.
If they see your a Google Adsense member, and your applying to YPN, they will see that you will stop using their competitors service and switch to Yahoo's. If anything it will increase your chances of getting accepted.
No it won't. The quality of the site and it's potential to increase advertiser's conversion is the main factor hands down.