One relates to the survival of such editors to being ongoing active editors. The second seems to relate to recruiting them and perhaps upskilling them for specific purposes, eg administration, guild of copy editors, and whatever initiatives you have in mind.

The first question probably relates to being able to get them better informed about the policies of Wikipedia at least in relation to the area of their contributions and how to engage with the community because it is the abrasive interaction with the community that seems to drive people away.

The second probably relates to raising awareness of WikiProjects and other collaborative initiatives. (Obviously all of WP is collaborative, but some things require higher levels of coordination and I think this might be what you are referring to). I think probably needs some analysis of the nature of their contributions and/or their topics of interest in order to introduce them to targetted WikiProjects etc that seem logical trajectories for them. The mistake we make constantly in onboarding newbies is overwhelming them with information (think of the standard Twinkle welcome templates) because "THEY NEED TO KNOW THIS" instead of what they want to know "how do I do this current thing I am trying to do". For similar reasons I think any attempts to draw them into particular projects/initiatives should be highly targeted, not too frequent, and based on what their interests seem to be rather where someone else would like them to work. (I think we should avoid the mindset of "I need to recruit some cannon fodder"). Having got their attention, someone probably has to hold their hand through whatever upskilling is needed to get them productive. Just pointing people at a Project page isn't helpful, there needs to be some human outreach and shepherding.

In some idealised universe, we should see Wikipedians as being on a learning journey, where (through analysis of past contributions and interactions) we are tracking them against a series of learning objectives (as we do with coursework curriculum "they have passed this unit, let's offer them some new units that build on that"). So, using newbies as an example, we look for some threshold of surviving-edits that demonstrate skills like "add text", "format text", "add list element", "make links", "make piped links", "add citation", "add templated citations", "use a template", "edit an infobox", "add an infobox", write on their talk page, write on an article talk page, write on another user's talk page, add to their own user page, etc. The idea being to suggest as various competencies are attained how to add a new skill to their repertoire. Once they have acquired the basic how-to skills, we could look at the suggestions of where they might apply these skills and how to specialise their skills in various ways.