Hayley - Jade has recently just started her terrible 2's. Oh joy. And as I am the only person who actually disciplines her and won't put up with her shananigans as it is unfair on Troy as he just get's left at those points.
This is what I do:
Naughty/time-out chair - works like a charm! Give her a warning for whatever she is doing. Usually putting up a fight to get dressed. I look her in the eye and say Jade let's get dressed or you are going to spend time in the chair until you are ready to get dressed. If she whinges to kicks up a stink again - in the chair. I usually tell - when you are ready to get dressed and behave then come to me. Or 1 minute for every year. Once she had decided she i ready to get dressed. I usually put in the passage away from our bedroom as then she is feels excluded from the family which she hates! She usually gets off the chair and says mommy I am feeling better now and then we carry on with whatever.
I explain to her that she was put in there because she was not listening. Kiss and hug.
Threatening and not doing anything does not work - my MIL and DH do that and Jade just laughs in their face practically. You have to follow through so they can see you mean business!
The food thing - what I do is put the food in front of her if she does not want to eat, then that's her problem and sometimes I might offer her an alternative. Julz is right they won't starve themself.
At the shops - I know this is bad but I do use a bit of bribery. Behave yourself and you can get x or sweeties or whatever. Or I just keep of feeding her while doing my food shopping - fruit, then some juice, nuts, rice cakes etc. Keeps her quiet. Sometimes she helps to shops and puts stuff in the trolley and while she is not looking I take whatever out. I am the one that just puts stuff anywhere on the shelves

I spend enough at woolies for them to tidy up after me!
Bed time - we don't have issues yet. Just got to lie there with her till she falls asleep. Which is fine cos I am usually feeding Troy at the same time. And gives me an excuse to lie and relax with the kids.