So with the Indian variant I want to know is it more transmissible? The answer appears to be yes but how much is under dispute
I'm not sure there's even actually much evidence of that, there's only strong evidence against original, not "kent" variant.
But currently, there is no evidence of efficacy for one dose against the Indian variant
No, there is evidence, just not conclusive, this is actually like most of the evidence for any of it. However given the more confidence that it is similarly effective with two doses (or longer time since first) then a hypothesis that "the vaccine works completely fine and exactly the same after 5 weeks, but is completely different until 5 weeks" is not a very likely hypothesis.
All these studies on effectiveness (including the original ones) are so sensitive to what's happening in the wider society that they need to be taken as indications only in my mind. The case reductions in vaccinated groups everywhere including India is the main reason to be confident, not looking at the differences in a few dozen cases in different communities in small towns/regions.