Another Potty training question? mommies of boys i need some expert advice.?

i konw its been asked a hundred times.but i need to read it here for myself instead of having to search for old questions.which way is best for a boy to learn to pee on the potty standing or sitting.the couple times i have gotten him to go it was sitting i had to pour warm water over his buggie to get him to go but it works and he goes and i clap and cheer him on and give him a treat after he is done.he is 21 months and the reason i started is cause he has gotten so he will hold it for a long time esp. if we go off somewhere.when he goes to his preschool thing for 3 hours sometimes he is still dry and when i get him home that is when i have gotten him to go pee.i have not been able to coax him in to doing the other on the potty.he does not like to sit still long and esp. not on the seat thing we got him to go on our seat to make it smaller for him.he acts like it hurst his legs.so my questions are

1. which is better standing or sitting
2.should i use a potty instead of the seat converter thing
3.how often and when should i sit him on the toilet this is my first child so im clueless
4.how can i get him to go without having to use the warm water to get it flowing lol.
5.and any other tips and tricks to get him to sit still longer he is the type to not sit still lol always on the go and the treat i used after he peed was m&ms.he loves em and thats the only time i have given them to him was after he pee peed