If you seriously want to load the bike up a bit for touring I'd just change the crankset for a MTB triple (26/36/48 or something similar is probably a sensible compromise rather than the more common 22/32/44) - your rear mech is likely to be compatible to accommodate that 11-32 cassette so it's just front mtb mech.
Don't worry about sticking with truvativ or keeping current bottom bracket, you can flog those together on
ebay for decent money to avoid spending extra on sticking to the one brand.
I'm thinking these two things plus some basic (borrowed?) tools, or cash to LBS will sort you out:
Crankset (includes BB):
http://www.parker-international.co....ogle&utm_medium=froogle&utm_campaign=pid13893
Mech:
http://www.parker-international.co.uk/13902/Shimano-Deore-M590-Top-Swing-Dual-Pull-Front-Mech.html
Just to check - is your front gear shifter compatible with a triple?