Calling jump balls

[Back In The Saddle]

I've done enough games now (20-30) that I've had a lot of questions arise. Through this board and a lot of study, I've found answers for most of them. However, there are a few that linger, and I hope you'll be patient with me as I ask a few more "newbie" questions

When is a jump ball a jump ball? How long do two opposing players have to be tied up before you call it? Do you call it as soon as you can tell they're tied up? Do you give them a second to see if one of them can wrest it away?

And what about fouls? I'm usually so busy trying to figure out if it's a jump ball that I don't watch for fouls. What SHOULD I be looking for in regards to contact in this situation?