Groupon spent a LARGE amount of money on marketing. They had a pretty large affiliate marketing program that paid out ~$2ish range I believe for an email submit. Affiliates blew this offer up.
I've been playing around with FB Ads doing some affiliate marketing stuff the last few months.
1) I think your target demographic, looking by the # of impressions. Try to go a little bit broader than just "tumblog". Try "tumblr", "blogging", "rss", .etc to reach a bigger audience
2) Your CPC is way too high. With FB it's best to go below their suggested bid, and gradually up your CPC amount until you start getting the desired impressions.
3) I'd gather a lot more data before making any kind of analysis on the data you're gathering.
4) Your CTR looks to be on the right track, although still probably not enough data to tell if it's stable yet. 0.1% is alright for a display ad on a social networking site. I'd still try split testing a couple different versions of your ad to see if you can up that. You always want to be split testing, constantly cutting the weaker performing ads, and making a variations of the better performing ads.