To respond to the other half of your question: the choice between rigid and semi-flexible.
If you won't want to walk on the roof, you may be better with a rigid panel. Of course the underneath will fill up with muck and leaf litter, because you should leave an air gap to allow cooling.
With semi-flexible, the idea is that the roof carries away some of the excess heat (anyway, there is no space to trap it).
And of course if it is on an even surface you can walk on it (handy for cleaning).
However there have been quite a few reports of semi-flexible panels failing after just a few years. I wonder if they were flexed too much before installation, or if there's not enough allowance for thermal expansion.
I have a fully flexible panel, which is nearly nine years old and seems good as new, but you can't get them any more.
I'd check about longevity before choosing a semi-flexible.