Problems adding graph to existing directory

I want logseq to make use of existing research directories. I have a few, with notes and docs and so on. I anticipate the following:

(i) me: easily incorporate old research files and assets into logseq
(ii) me: import them, or include/exclude them by pattern
(iii) logseq: simply see them, and allow me to access them through its interface
(iv) me: opt which ones to index, either by individual selection, by command when one of them is open in logseq, or by include/exclude, and with patterns
(v) me: edit the same files in vim
(vi) me: use the same files in Obsidian
(vii) me: I dont want to create a new research system that is divorced from my old one

What can I do?

I see that there is a user manual with some relevant info. I see that might help me incorporate existing markdown files. Just text files, pdfs, and so on, still to go.