Business names are not indexed in this project, just skip it.
I could be wrong ...
From your 'Question', I believe that you you could be "Indexing" ..
But, just in case ...
I am "Tagging" this (General) 'Question' of yours, in this "Community.FamilySearch" Forum, to the 'Group' being "Indexing Chat", in the Forum; so that, the members of that group can answer/assist you.
ps: That Group is "Public", which you can join, if you wish.
If a surname like "Brett" has handwritten beside it, "See Britt" do you index it as Brett Or Britt and would it be that way for all the records that follow with the same last name?
Yes to both. Index it as Brett or Britt and us that as surname until a different surname is listed.