Try opening up the tslpatchdata folder, and extracting mandoflamer.uti and spells.2da. I think that should do it.
No, it wouldn't. Spells.2da in tslpatchdata folder is not modded, so it don't have the flamethrower row (this row is added during the installation).
However, I can send you separate flamethrower mod (by LitRidl), which I used as base for my flamer. PM me your e-mail.