I agree with Abraham's comments.

"The pills will be living, but not fresh and maybe not "healthy", meaning that they're old and in a dormant state." This jives with comments I've seen in alt med books -- probiotics are often freeze dried and I assume "dormant," so full reactivation of all organisms wouldn't be likely. In one book I have it claims that cultured products (yogurt, kefir, cold sauerkraut, etc.) essentially contain the "whole package" of compounds which allow the beneficial bacterial to thrive, while supplements merely contain the bacteria. That said, I've known knowledgable people to claim that such-and-such probiotic capsules "implant very well," suggesting that capsules can work just fine, at least in some folks.

"The commercial kefir is basically yogurt from what I understand." Based on the ingredients, I'd agree -- commercial kefirs are milk-based products. But one big benefit for kefir is the lack of S. Thermopolis and L. Bulgaricus, the two primary starters with are required by law to be called "yogurt" in the U.S. Neither is a viable intestinal probiotic -- they're simply good thickening cultures -- yet they take up valuable space which could otherwise be dominated by Acidophilus and Bifidus. Kefir has no such legal requirement.

"How much kefir should I drink?"
Don't know, but Helios suggest the following: "If you drink 8 ounces per day, you will be giving your body a healthy dose of the beneficial bacteria that need to be replenished daily. For children we recommend 4-8 ounces per day." I'm sure you could apply this to Lifeway kefir as well, if you prefer to buy, rathre than make, the stuff.

I'm not familiar with homemade "grain" kefirs, and must defer to others on same. Helios states the following...perhaps we're talkin' some semantic confusion here??? "The key ingredient to kefir is the quality and authenticity of the kefir “grains” used in the starter cultures. Kefir “grains” are not real grains; this term is used to describe the cauliflower-like appearance of the natural clusters shown in the top picture."

http://www.heliosnutrition.com/html/kefir1.html
http://www.heliosnutrition.com/html/kefir.html
http://www.lifeway.net/faq/faq_index.html