My friend was on it.
Yep they certainly heavily influence the conversation and shit stir by dropping hints as to what other contestants had said. They also do it blatantly 'so, x, why don't you tell Y why you absolutely detested her starter?'
They also made her cook things at the wrong times. And recook things to get a decent shot - which made it difficult to prepare something tasty.
She was on it last year, so this may be a recent thing, but they were very strict on how much they had to drink - just a welcome drink and no more than two glasses of wine. They wouldn't let them have shots. They said this was because the evening went on too long otherwise - but they were still filming into the early hours.
The taxi goes round the block when you give your score, and then you go back and wait for a normal taxi to pick you up. Some of her fellow contestants lived up to sixty miles away.
Also, because of this, the food is pretty much all cold by the time you serve it but you're told you aren't allowed to score them down because of it, which is fair enough.
They also told her what props to buy from her own money but I think they give her an allowance of about £150 to go towards food and wine.
She was on an hour long show, so whilst they all had to have entertainment, this was only shown for one of the contestants.
She enjoyed doing it but was a bit disappointed with how she was portrayed - partly her own fault though as it was clear what the producers had cast her as and she did play up to it!