Some of those have alot of hinge fractures on the edge (multiples) Definately used as tools. The preform thing is a tougher question as preforms are sometimes used as tools.
Hinge fracture, is where the flake has detached and left an area where the material that has fractured but not detached........... In a nut-shell, The edge left at termination of a flake. You would easily understand if you looked at what I am talking about through a micro-scope.
Tools and scrapers and possible preforms. Remember a preform may have started out as a point but in a sec they could see a flaw in the material maybe a step or hinge fracture or a big ole bump they could not get a grip on to knock off so would knock off some edge flakes for a little serration and have a tool or knife etc. My humble opinion.
Yes you been someobne to recommend some good reading for you on your area.You are missing half the hobby with out understanding the material and lithics. I am also backing up from my collection and seeing what the story it has to tell............. I also learn on here,.
Regards
TnMountains