Thinking of starting to kettlebell. I have been poking around, getting some information and have a couple of questions.

1-I have fibromyalgia which brings with it the most ridiculous exercise intolerance. Anyone out there with fibro kettlebell? If so how does it affect you?

2-On a scale of 1-10 with 1 being bedridden and 10 being Mark Sisson, I am probably a 4. What size should I start with?

3-Walmart has the Cap bells. They are filled with concrete and covered in vinyl as opposed to cast iron. They are about $13 less. Is this a viable alternative?

Thanks for reading and providing the A to my Q's. (and yes that was more than a couple of questions, but only one more. So I had a few instead...semantics)