So vague an answer.

You can make money from a game if it's not a fangame, i.e. Dragonball Z/GT, Naruto, etc... This can be in the form of a subscription or donation. I am not too aware of any other procedures for raising money unless you are participating in the 8k Challenge.

You can host from your old computer on certain conditons. One would be that you aren't using a dialup modem, because it's nearly impossible to host on one. Another would be that you have your modem and/or router configured if they weren't already. Lastly, there are a number of things that can protect access to your computer from other IP's, such as a firewall, virus/worm protection, or an antispyware system. Be cautious of those.