Reddit mentions of Trails of the Sawtooth and White Cloud Mountains

Absolutely!

Here's the website for the trailhead\campground (no fees for backpackers).

I think the best resource for hiking the area is a book by someone named Margaret Fuller. It provides in-depth info regarding the trails and destinations, as well as some great ideas for the different loops you can do.

Pretty good resources:

http://www.amazon.com/Trails-Sawtooth-White-Cloud-Mountains/dp/0966423380/ref=asap_bc?ie=UTF8

http://www.amazon.com/Trails-Western-Idaho-Expanded-Updated/dp/096642333X/ref=asap_bc?ie=UTF8

It's not just bears you have to worry about. You also don't want little critters chewing through your expensive gear to get at interesting-smelling stuff. It's always a good idea to hang food, toothpaste, etc:
http://www.backpacker.com/skills/how-to-hang-a-bear-bag/

You can find hiking and backpacking groups on Meetup.com

If a gun gives you peace of mind, by all means take it. However, it's definitely not a necessity and I've never seen a backpacker carrying a gun in Idaho.

Good luck!