I'm taking into consideration his quip at the end of Time Heist (since I marathoned all the episodes, I might be inferring things differently) when he mentioned that robbing a bank would be better than any date she'd go on. I can't remember the line but I think that's what was implied when she left to go catch Pink at 7:30. 

I think "flirt" isn't the right word to describe the odd relationship between Clara and 12...but it's weird and forced and keeps changing. One minute she's mad that 12 doesn't visit for nearly two weeks, the next minute she ditches 12 to focus on her life, the next minute she's upset that he wants to do something without her, it just seems weird and inconsistent. 

I understand 12 not liking Pink, he never was a fan of soldiers though, I thought that was one of his 'things'. The saving grace of the episode was Pink understanding where 12 was coming from at the end, otherwise there would cue another pointless triangle of jealousy and trust issues...