Yeah, it sounds like you want a mix of things done. Editing (in the traditional sense) is usually related to the script. Like adjusting dialog, refining the plot, checking for typos, ect. You can probably get away with paying someone to edit a whole script. Maybe $20 for 20 pages on a place like Upwork. But if you want a pro, it'd cost a lot more.
As for tone/color: you can find tons of people to do that on comic forums like Digital Webbing or Pencil Jack. Pro rate for coloring can be $100 a page, but I think you can find people willing to do it starting from $10-$20. Chances are you'll get a better colorist for more money tho.
Same for a letterer (speech bubbles), you can find them on Digital Webbing or Pencil Jack. But you can do that yourself really easily with software like Manga Studio. It costs less than $50 (and is really easy to letter things with) which costs less than hiring a letterer.
Anyway you go tho, I wish you luck with your comic!