Oh yah, that is true (about playing games on a TV vs a portable).
As for the battery life of the PSP, you will get a minimum of 5 hours of constant game time with one charge, however this is highly subjective. Adjusting volume and brightness can greatly increase/decrease this number but on average 5 constant hours of game time is what I've seen. Sony has already announced a new battery that has 30% more life, so I'm not at all worried about it.