"if they like you, they'll love your magic."
If they like you, they are more likely to like your magic.
It's not an excuse to slack on the magic, and also some people still don't like magic. For me this saying means that people will go along with you, so if something should go wrong, then you can all laugh it off together - I've got to a point, where I can save routines, so if I reveal the wrong card, then I can switch it for the correct card or do a colour change, and everyone thinks that was part of the original routine.
The restaurant pays - count on getting no tips in a restaurant, and therefore any that you get are a bonus. The most I've got was £9 during a two hour shift, usually it's nothing or £2 or £3.