Thank you for your feedback. Forgive my newbiness, and here it goes again:

Doug: from what i see in the sheldon brown calculator, a cassette for 14-34 needs to be 9-speed, correct? Is it because i need more speeds that i need to buy also new derailleur?

AngrySaki: I visited a store today, and a brand new cheap shimano 22-32-44 was exactly what the dude proposed me (he said 30€). He said it should be enough, but i'm really carrying heavy load, tent, kitchen & food, and 22'' as lower might not be enough as chasm54 pointed.
Also, the guy said no ring could be changed alone: all the crankset needs to be replaced.

So, assuming that i would keep 7-speed in the back (mega-range freewheel 11-34), with a new 44-32-22 crank set i would have 18.1'' as granny and 25.7'' as a second gear and 26.4'' as the third. I know they're kind of spaced, but my point is to travel, even if i do it slowly (as i said, steep mountains are a fraction of the trip...) Does this sound stupid?