As for your first campaign this is definitely one that you can do A LOT of volume with but you're going to have to find dirt cheap traffic or begin isolating multiple variables until you can find one that yields a good EPC. If it was me I'd go on the hunt for an ad network I could get traffic lower than a penny for. Going to take some negotiating but that would be my first suggestion. As far as isolating variables you may want to take just one manufacture (ie: Samsung), one OS (ie: Android), and one carrier to see if you can find a "profit pocket" that can be exploited. I know your initial test didn't find one but given the amount of volume it could take a MASSIVE budget to test that out. I'd prefer to conduct several mini tests with a couple of variables.
Hey nice ROI on the second campaign! Good job! Let's see if we can't scale that one up some more!
Also good job on the revenue. Keep us posted bro.