Measuring my frame

where does one measure from to on top tube and seat tube ?

is it centre of the headtube to the centre of seat tube for the top tube measurement
and top of seat tube to middle of bb for the seat tube ?

Yes.

That would be Top tube (C-C), seat tube (C-T), which is most common.

Silly really as the amount the seat tube extends past the toptube is'nt actually standard.