Ok so if I side with the NCR will I get more stuff than siding with yes man or vice versa

It's not about "more stuff " per se, it's about getting a different ending slideshow.

Not necessarily, since in both cases you can complete the quests without killing anyone until the battle at the dam. That said, if your character has a low Speech skill* then going the NCR route will get you access to Quartermaster Bardon and his massive ammo stocks once you reach the point in For the Republic, Pt II where Colonel Moore grants you permission to buy from him.


*If not backing the NCR then you need at least Accepted reputation with them and passage of a [Speech 50] check with him for him to sell to you; the former is fairly easy to get, while the latter depends on your character's development.