Not cow tipping.

So like how do you handle tipping in the following situations:

1) Pizza guy (around here the pizza places charge $1-2 extra for
delivery anyway). Do you tip based upon how much you ordered (dollar
amount) or a flat amount? And how much?

I do flat amount, $2-3 (depends on how long they take. One time they
took 2.5 hours to deliver the thing).

2) Delivery guys (like you paid for delivery of say, a Fridge or
something). Do you tip? What if it's a straight-forward delivery (like
back the truck up, go up 3 steps walk 20 feet and set it down). I
usually don't tip (but I may be apparently offending someone), unless it
was like an "effort" delivery (like when I had my wide screen TV
delivered they had to have 3 guys and take it down a flight of stairs
and it was like 250 lbs and stuff).

3) Chinese food. Flat fee or what? (20 minutes is our standard
response around here for delivery even if it takes 3 hours).