S.T.A.L.K.E.R.: Shadow of Chernobyl Q&A

I've found the documents in the Lab for the barman, but now I can't get out because something is holding the door, how do I get out?

I'm not getting the option to press f to open door at the traders anymore. Therefore i have failed giving him the psuedo dog tail and some other one that i cant remember right now, anyone know whats goin on?

Half way throu the game
it crashes and it sez it has
a bug and it wont work any more

in the sewers how do u get past the invisible monster and the military soldiers its so hard!!!

How do you fire a vog-25 grenade frm a grenade launcher?

how d'you fire a gtrenade from the TUNDER S14?