I can’t answer all your questions, but for the 5th: the spike protein is most definitely cytotoxic and my guess is that they are not at all attached to the membrane (as nor is covid particles remain attached), effectively solving 1 and 2 of your questions. As for the cytotoxicity, they are made in a locally high but overall very low level compared to even a mild Covid case, so the effects of that should be less than what covid would have been. About 4 I read that basically every foreign protein in the blood stream can potentially start platelet aggregation, so there is that.