Hi
troppo32, glad that you've liked the mod.

Extreme mode can be chosen during the installation of the mode. The installer will ask you to choose one of the available modes, then you need to tick the box for the Extreme mode. Once you've started the game, and if you haven't chosen the Extreme mode during the installation, you can't change the mode of the game during the game. You need to re-install the mod choosing the option you want. (This is true for all other modes of the mod).
You might've probably already installed the Extreme mode; to see what mode that you're playing, just look at the bottom of the main menu screen as seen on your monitor. It should tell the mode there.
Wombat_70 , I might strengthen the Colonel character a bit more with the new patch. None of the offered solutions are complete on those links, or quite practical to achieve to what's wanted, and, as Balious also points, such changes (depending on the changes) may end up altering the other NPC strength standings. Fatrap had a spefic idea on his mind he wanted to make that sniper very strong (not immortal, though) ; but dealing with other characters' strenght positions may prove counterproductive, as it may change the game to a sort of "scripted" game like some FPSs, where some never dies, while others always die, etc. The game here
acts organically to the events, characters engage with enemy and depending on the nature of their engagements they may survive or die, (or get wounded) in the long run, which I believe brings to the game the element of "unpredictability" and urges the player to get involve with the events and characters more, as sometimes either it becomes necessary to save a character, or just one doesn't want that character to die.
Saving often helps having more a creative game full of alternatives, and if things go unexpectedly (that's the beauty of it

) then the player may need to decide if he should reload and try to support those characters, or let them rot there.
But if the Colonel is seen to have been dying a lot, then a small adjustment may be done.; but needs to be evaluated and tested well to see the adjustment is neither over nor below the "just good" level.