I will beta-read your fanfic! I am pretty open to any fandom and most subject matter. I am currently a huge fannibal, but I cut my teeth on fanfic in the good ol' days of Naruto and Harry Potter Fanfic, with a dash of My Chemical Romance to go with. (if that utterly dates me).
One "unit" would be one chapter, or 2,000 words, whichever comes first. So, if you have a 6,000 word chapter, I'd consider that 3 units of 15 simbi each.
Training & Qualifications
I am actually currently getting a Master's in Publishing, editorial track, so I'm good with helping with development and also finding errors in continuity or grammar.
I have also been into fandom since the dark days of Fanfiction.net, for probably 15 years or so now. So. You could say I'm a fandom veteran.