I would never, ever, ever, mention the size of a man's penis to him other than to tell him it's perfect.
It's not something that requires "discussion" at all.
Re the vegan, if veganism is such an important factor for him then he should pre screen and only date vegans! Having said that, I wouldn't be talking to him about meat and if he bored on at me about being vegan I'd sack him off anyway (my most recent ex decided to become vegan, he was dreadful at it, and it was more of a try out, but he never stopped bloody talking about it, I did it with him, it was interesting for a while, but my god he got so dull about it, but then he did seem to only ever be able to think of one thing at a time!).
Re the text after date - same for me with MrGig, he's not followed up at all after our date last Thu, other than to respond to my text the next day. It's the first time in all my dates over the past year (I think that is about six, not sure, not including MrWG) that a guy hasn't wanted to meet up again.
I didn't feel much connection with him, though he was nice enough, so I'm not bothered at all.
Am away at the moment but just waiting for MrBee to suggest third date, we've both said we'll meet up again. He's not much of a texter though. I didn't go for scones at his house, but we had a nice day last weekend, so I've said he owes me a scone.