Disagree. Hunspell and aspell have tex modes that understand well what needs to be checked and what doesn’t.

Comments can be added with ‘%’. Just make sure to have a linebreak at every sentence and it’s cleaner than anything. Services like overleaf also exist for collaboration.

You can use any versioning system you want. From git to dropbox, its plaintext.

I do agree that layout can be very time consuming, but it helps once you learn to not care about it till the absolute end of working on the content.