http://www.uesp.net/wiki/Skyrim:Respawn
That every time I enter Faendal's house (with him as a follower) the "respawn counter" is reset, and the respawn time on his house is 10 days.
What I conclude form this is: as long as you return there more frequently than 10 days, you could safely store your stuff in the container's in his house?
Never have been much on main quests and periodic dragon attacks because my High Elf is supposedly some "dragon shout dude" doesn't appeal to me intensely. If he was a Nord, yeah sure, but mainly i'd just like to ( a ) have a place to store my excess junk that is pretty close to Whiterun while I level upa bit more; ( b ) not feel forced into the dragonbore stuff. Seems like, apart from the Companion's (which a High Elf Mage guy wouldn't seem to be too keen to do) Faendal's house is about my best option?