We used Biolite solar panels for this deployment. We partnered with Biolite and they kindly donated 5 panels.
These nodes have been live for ~30 hours so far. I would recommend using at-least a 5W panel with a minimum of 2200 mAh power back up. This ensures that goTenna Mesh will have enough back up power even if the sun is not out for multiple days at a time.
Yes, we are looking into this. Increased # of hops and the USB SDK is much further along and will be part of the next release.