There is very, very mild violence and some trolls, giant snakes, and such.. I wouldn't bother getting HP for him since he probably wouldn't understand it anyways, but it wouldn't hurt him to watch it with you if you're wanting to watch it.
Not REALLY - and Not only the Young Age or Necessarily the Content but there is a Lot of Hidden Content and Agenda that Comes Out And Pops Out ---- Harry Potter and Its Content is Believed to be of the devil ...
it depends on what you are concerned about.... their is minor cussing, not really any sexual content. but it does involve magic and wizardry obviously so if you are ok with that then he should be able to watch it. their are some scary parts so you might want him to "close his eyes" and it also depends on if he wants to watch it or not. if he is into all things harry potter than go for it but if you guys just want to see a movie then I might wait a little longer... its really up to you and the level of "strictness" you have... hope that helps!! :)
I think it would be bad. Studies show that by the time a child hits 8 years old they have determined what the world is like. I would be cautious of what you are putting into there head. Witches, warlocks, magic, etc. I would wait till your child gets older before you subject them to that kind of stuff.