I know of a few trees of this species, and all of them are isolated, and fruit very well on their own, so I don't think they need more than one to fruit!
About how long the flowering last, I'm not sure, but I now that both flowering and fruiting are not uniform, and you can have sometimes flowers, small fruits, and almost ripe fruits at the same time, wich means you can never harvest all the fruit at once, sometimes even in the same raceme.
About shelf life I have no idea as I always eat them directly from the tree, and never tried to save some to see how long do they last.