I would say stick with the german market honestly. The english speaking web hosting market is huge over here, I hate to say it, but I doubt you would experience much success.
I have used cpanelsource for cpanel. I have always just rented whmcs directly from whmcs. I'm not sure there is much of a cost difference. Please use my affliliate link for whmcs if you decide to get it http://www.whmcs.com/members/aff.php?aff=3712