Don't bother to get separate poles. I just use my same old trekking poles for snowshoeing or even cross-country skiing.

What brand do you have? If you have Komperdells, let me know, I have an extra pair of baskets that don't fit my poles. Check on the maker's website or if they sell them at REI, Campmor and so on, they may have the baskets. REI lists baskets for Komperdell, Scott and BD on their website. I have Leki poles and got baskets for them somewhere. A16 or Sport Chalet maybe, can't remember.

There isn't that much difference between trekking poles and collapsible ski poles except you won't find the shock absorbers in ski poles (don't think so anyway).

Snowshoeing isn't rocket science. There isn't much to it-figuring out how not to step on your own feet is about all there is to it. Turning around involves taking small side steps, outside shoe first (turning left, left foot first) otherwise you cross the back of the shoes and will trip yourself.

There are a few good books on snowshoe trails in CA-Michael C. White has books on Yosemite (Snowshoe Trails of Yosemite) and Tahoe. Got mine at REI or B&N, but Amazon should have them.

I carry a pack with extra clothes, food, canister stove, snow shovel, small sit pad (cut from a cheap blue sleeping bag pad, ten essentials-map, compass, etc.

REI sometimes has snowshoe classes at the stores and rents snowshoes.

Royal Gorge at Tahoe has miles of trails for XC skiing and snowshoers are welcome there-they rent snowshoes too, according to their website. I havent been there, but their website shows they have huts, cafes, pretty much anything you could want, plus a lot of beginner trails. It looks like a big ski resort,except not for downhilling-although it does have a few lifts for the steep parts for the more adventurous skiers, I suppose.
www.royalgorge.com

It is mostly flat or rolling hills from what I can gather from the website, so no avy danger. They groom the trails for skiers, and the snowshoers would follow the same trails, but off to the side (or maybe the middle) so you don't damage the ski tracks they cut into the trails.

If you can get to Donner Park at Donner Lake (you may need a car), that is easy, safe terrain. It is near Truckee off of 80. If you do go to Donner-don't buy a Sno-Park pass-it isn't good there. It has its own parking fee.