Xbox – If I have Xbox live gold will others on the system be able to play Halo matchmaking

I would suggest buying your son a prepaid card. You do have to remember when it runs out and buy another, but they tend to be $10-15 cheaper than buying the same amount of time through Microsoft directly. It's also much easier to stop being a subscriber, since you just don't add more time to the account - no need to figure out how to stop the automatic payments.

In order to play online with an Xbox 360, you must have Xbox LIVE Gold, which is a yearly subscription. This includes Minecraft for the Xbox 360.

Minecraft on the Xbox 360 supports splitscreen, and if you have one Gold account, other people playing on the same console can participate online without needing Gold accounts of their own, as long as they are logged in as a Guest.

However, each Xbox 360 that you want to play on simultaneously will need to also have at least one unique Xbox LIVE Gold account. This means that any of his friends who are playing from different locations will need a Gold account as well, and they can't share the same one.