Try out the complete mod, that one doesn't attempt to alter the game play, it just tweaks a few things, irons out bugs and generally gives it a face lift.
Re : combat, I always found that with Stalker when it came to the enemies throwing grenades, it was best to treat the situation almost like a multiplayer situation!
They have an amazing accuracy at times, and they won't hold back if they have one to spare. I tended to pull back a bit, reminds me of the map 'Office' on cs:s, once through the garage and aiming through the glass windows you often see people get caught out with nades there.
As said don't go in gun-ho, until you get used to the game and / or are powerful enough it probably won't work. If by some chance you do make it, what with the organic feel the engine delivers, you're bound to attact the attention of a mutant nearby.
Here's a few more Stalker : SOC shots, Oblivion Lost mod. Several 'Freedom' soldiers came along for the adventure - at one point I had well over a dozen following me! (Sorry about the gasmask
)...exucse the lack of AA, not sure why but I find this mod seems to have a bigger impact on performance than compared to 'Complete'. I can use AA but then I am at the mercy of using 'box' which sometimes doesn't look up to much and edge-detect is borderline too much of a performance hit for my liking. Unfortunately, SOC doesn't seem to utilize AA like Clear Sky does iirc.
The one below is where I genuinely had one of those jumpy moments, my crosshair went mad - I do hope they give a selection of choices for these in future. As I was checking this dude out...another one appeared seemingly like from nowhere..growl...
This mod seems to allow you access to vehicles but not to power them, though most look like they need a service, I doubt an m.o.t certificate would be necessary.
I got into the tractor and my supposed friends knocked it over.
