Hiroshima – Kansai pass

I'll be in Japan in two weeks and I was considering the pass since I will be staying in Hiroshima and Osaka. I have a few questions that I still have no clear answer on:
* Timer starts ticking the moment I pick up the pass at a station or the date that matters is the one I pur when buying it~?
* I saw it can be used for the Wakayama and Kyoto tango railway but given they are usually in high demand, can I reserve a seat on them with the pass? And if so, where do I do those things~?

Any info will be greatly appreciated~.