I would think most merchant account providers would accept them. The only issue you may run into is if you charge large annual fees for having a listing there. Some providers may shy away from that due to the enormous chargeback potential but otherwise you should probably be able to choose from any provider you want.
That's not an issue. In fact it is very common. BTW, avoid that website mentioned in that last post. They only posted it because it contains an affiliate link. Alertpay is only good if no one else will take you.