#1
NZBSearch app permits you to search and download an NZB locally as well as send it to SAB.

It'd be nice to get the same functionality for those of us who have PoweNZB or even NZBGet running on our androids.
#2
There are apps for that on GP.

You could also download the file from the 'Details' pane when you click on an item in the searcher.

Maybe an idea would be a 'Long press' on the send to sabnzbd button for manual downloading.

NZB360 is an app intended for managing your remote services. It's not really made for local (android) download clients.
#4
You can already download a file locally by sending it to a local downloading client. I have nzbget running on my android device and sabnzbd on my server. Hence I can download it locally by sending it to Nzbget instead of SABnzbd
cron