I'm sorry that no connectors have responded to you before now but I think the reason might be that we can't truthfully answer your two questions. But saying that I might be able to go part way there.
So the first question was getting an unconnected list of high contributors. The main problem with this is identifying the high contributors in the first place. If you work on connecting in a particular location, then you may soon start to come across many unconnected profiles that were created by the same profile manager. In that case you can run two WikiTree+ reports, one for their unconnected profiles, the other for connected profiles. If you sort both reports by last name, then scroll through each of them looking for names that match.
I've run the report here for you, you'll see that in the search criteria box you have the words unconnected keil_336.
And to run the connected report for yourself, use the search criteria connected keil_336. (Note it's underscore rather than hyphen in the Wiki-Id)
The second question is not at all easy to respond to. You firstly have to identify a Gedcom name that has many unconnected profiles, this again may be something you discover when connecting in a specific location. Once you have found your Gedcom name, then you'll need to identify profiles that were uploaded within it.
Open your profile page, then select Find (top right) and Search. Scroll down to the bottom of the page to Section 4. Put the name of the Gedcom in the box and press GO. One that is being looked at at the moment by another WikiTreer is Tonkes_Morris_Ryles_Ellis.ged. So maybe run this and see what you get. There are loads of both connected and unconnected profiles from this Gedcom, and they are gradually being put back together again.
Once you've run the search, you will get a list of links (it uses Google) to profiles in that upload. But to find the unconnected ones, you have to open each of them. It's quite a slow task but if you keep a list of connected and unconnected as you find them, then you may be able to start to join the profiles into family groups.
If you need more help with this then maybe send me a PM and I'll help as much as I can.