I haven't been to yoga classes for maybe 15 years. There are now many "newer" forms available. Many use objects: ropes & chairs etc. I tend to just use myself & gravity. That way I can do it anywhere like eg when travelling & staying in hotels. I guess I perform a type of hybrid yoga, but mostly based on "Hatha" yoga. A friend of mine is a yoga teacher in Queensland (northeast Australia) & that is Iyengar yoga ( yes, I think the spelling is correct). I've done classes with her & enjoyed that too. I'm not really a purest as far as style of yoga, I just stretch where my body tells me it needs it. After cycling I find it invaluable. I cycle with an ex-professional & he reckons he hasn't done any stretching in 30 years! He still performs outstandingly, but his comments blew me away.
You won't get the strength in the short term (as with weights) but over time your body will be stronger systemically. I'm 49 years old & the disc spaces between the vertebra are those of a 25 year old. I have "back problems", but they're facet joints wearing out rather than discs herniating (as can happen with weight-lifting & general ageing).
As far as the protein powder, mine doesn't have added calcium, but I do take a supplement. Thanks for reminding me to take it regularly. I hope you find yoga beneficial for you.Cheers.