Tone - I've experienced four different setups when it comes to the relationship between audience and folk performers:

1. Audience Listens, You Play (old-style FCs, particularly if unamplified)
2a. Audience Talks, You Play (pubs & bars who put performers on as background music, particularly if amplified)
2b. Audience Talks, You Win Them Over (like the previous, but people have come expecting to be entertained; you can get them on your side with The Wild Rover, but you'll lose them halfway through Plains of Waterloo)
3. Audience, What Audience? (if you're in the room you'll be asked if you've got a song, probably more than once)

1 and 3 are fine in my experience, but both the 2s are pretty awful. You're currently stuck in 2a. You could go for 2b, although I wouldn't recommend it - I was in a pub session once which was organised on the basis of (a) sing or play what you want but (b) entertain the rest of the room, and it wasn't ideal. Or you might have a chance of going for 3, if there's a room you can commandeer - how big is the pub? I don't think you can get to 1, though - once people get used to talking over music they don't want to give it up.