Yes vectors indeed provide the operations needed to perform projection
Yes indeed it is compatible with matrixes, aka CFrames in the context of Roblox
Yes you can reflect vectors, it’s called the unary negative operator
And for stuff like lerp you can again implement that using the base operations of vector, which is why i said your library isn’t made obsolete by vectors, i’m saying you can gain alot of speed by using them and making mathsm.Vec simply provide additional operations like lerp and project.