Inf Ammo :
As it says (No Reload)

Pick Gun IGK (Rt+Lt) :
Press R-Thumb + L-Thumb To Cycle Thru Guns

One Hit Kill (Gun) :
Spiders die with one shot

Inf Health (Kong) :
I didn't find this, thank the game saves pimp

Unlock All :
As it says

Everyone took a stab at this, lampo, acidflash, and
dootdoo.  We all got a little bit of it done, so here ya
go.  Big Props to FNG for his killer save, and info.

Ooops, I screwed up earlier.. Inf Health crashed the game,
and the Unlock All didn't work under some system configs.
These have both been fixed.  Please note the inf health is
ONLY for KONG!! NOT JACK!