Hi Jessica -
I have used a couple different pedometers. I have returned two because they were not registering my steps accurately. I took 100 steps on the treadmill, and compared my count to the pedometer. I like to test things to see if they work as their supposed to. I buy from stores with a good return policy, and haven't had any problems returning them if I think they are innaccurate. Different ones work better. I have a couple now that work clipped to my undies, when I'm in my stocking feet doing morning chores. Oh, they also work when I'm out walking in shoes around the track.
The reason behind the 10,000 steps recommendation is that it is figured to be about 5 miles for most folks. So, yes - each mile is roughly 2,000 steps. A lot depends on your stride length - it's usually described in the info with the pedometer how to figure it exactly... I just wanted the pedometer to remind me to get more activity, so I didn't do the measuring routine.
If you note the # on the pedometer, and do your leg exercises, you can judge for yourself if you are making it advance with your exercises. Some of the brands are more sensitive than others. I have one that works well while I walk in bare feet and another doesn't. (I wore two and compared step counts, and also counted some steps too here at home doing household chores - just to judge their accuracy).
I've bought some $10 ones and some $3 ones, and find both to work equally well. I haven't tried any of the more complicated and expensive ones. I just want one to remind me to keep moving and not to be a couch potato. I actually like the little $3 one cuz it's smaller than my others, and less noticeable when I'm out in public.
For me, I prefer a treadmill to an elliptical. It is easier for me to do an hour on the t'mill - I like to go for 45-60 min to burn the fat. I don't think I could last that long on an elliptical (knee problems).
I hope I answered some of your questions. Pedometers are fun. It's fun to see how many more steps you can take by parking farther away from the stores and also just browsing aisles once inside. It's a great little toy for me. I hope you have fun with yours too.