1.
I would like to change one of the ones your co-teacher had already:
"you should blah blah" instead of "do blah blah"
Personally, i HATE it when I'm told I SHOULD do something, and I actually made a whole lesson around the difference between SHOULD and MUST (choice, no choice. respectively) because it is the same word in Korean.
Rather, I tell my co-teacher to word an order as a question.
Eg: give me the papers
--> could you give me the papers, please?
And I explain that even though it's a question, we understand it as an order. It just sounds more polite.
2.
Yes, ALWAYS ALWAYS ALYWAYS SAY PLEASE
my co-teacher actually came to me the other day and DID say "give me the papers". Even though I knew he didn't mean to me mean, all the bells in my system went off as "whoa...don't take that tone with me, mr."
So I was equally rude (because I lack finesse...) and dangled the papers saying "PLEASE give me the papers".
What was frustrating was that he said "yes"
so I repeated myself again. "PLEEAAASE Give me the papers"
He looked perplexed and scared.
Finally I had to explain that I wanted him to say please.
He then divulged that he had pondered over this in his office before coming to see me (as you know, all conversations with your co-teacher have been pre-prepared, thought out, and memorized before hand) and debated over whether or not to say please.
In the end, he decided he did not need to because I was younger than he. So I had to explain that you say please all the time in English, regardless of age difference.
(whoa, I'm getting as wordy and roundabout as smee in my replies

)
3.
Foreigners don't eat the same thing every day for every meal, soo....
a) Asking "what do you eat for breakfast/dinner" is an awkward question requiring more time for an answer than you're expecting
b) Please understand that sometimes we don't want plain white tasteless rice for lunch (on your behalf, V. I eat it all the time, but I understand completely)