how many weapons we'll we see in rage.

Depending on whether or not you get the Anarchy edition, the standard amount would be, from what we've seen (and what I remember), 10, and then with anarchy edition, 12, if you include the fists of rage as one.

So the list would be, from what I remember:

Shotgun
Wing stick
Settler's Assault Rifle
Authority Machine Gun
Crossbow
Personal Turret
Rocket Launcher
Spider drone type sentry turret
Pistol
EMP grenades

And then the weapons included in the anarchy edition:

Fists of Rage
Double Barrel Shotgun.

I'm probably forgetting plenty of stuff, so I'm not totally correct on this. But that's what I remember.

Sniper rifle and AK47 but it could be settler's assault rifle.

That's not a list of 'guns' thats including some gadgets. There is also a rocket launcher and probably a grenade launcher. Keep in mind there is a split between gadget/thrown stuff and actual guns as the gadget/thrown objects are separate 4 button hotkey and gun has its own specific inventory page and 4 hotkeys. How many? No idea to be honest, they haven't shown everything but the RAGE Wikia lists out a good amount of stuff.

Pistol
Crossbow
Shotgun
Settler Assault Rifle (AK47-ish)
Authority AR (with scope)
Authority Plasma Rifle
Sniper Rifle
Rocket launcher

That's just off the top of my head, like I said I'm sure there's a grenade launcher and probably some larger full-auto weapon. Maybe another type of pistol as well. Just think of there past games, there's a good chance there's at least 10 weapons including some crazy over the top energy weapon of some kind or another. Then on top of that you have different ammo types for 'all' of them altering how they function to some degree (like explosive rounds in a shotgun).

And then, of course, Gadgets which are some of the stuff poster above mentioned, Sentry guns, Spider bots, Wingstick... they all seem to have alternate version as well. Like strapping a bomb to a wingstick. From what I saw of a few of the videos with the glimps of the Inventory looks like the 'inventory' is for gadgets/thrown stuff and things to 'make' stuff via the engineer tab. Weapon has its own Tab where you carry all weapons available to you but can only have 4 things bound at once. So you have 4 quick-swaps but can still pull out a bigger weapon if its required. For instance I'll use an AR/shotgun/sniper most the time... but the option to pull out that rocket launcher if a giant mutant shows up is available always.

i think you get different ammo types for each weapon as well..

there is also that gun at the end of the well game play footage that looks bad ass