How do you measure edge straightness of lead frame?

with a ruler or anything that you can measure with

The two most important measurements are center-to-center for seat tube and head tube(top tube length), followed by the seat tube height, measured from the center of the bottom bracket.

The easiest way is probably using a caliper micrometer.

There are two basic measurements: center-of-bottom bracket to top of seat tube/center of top tube. The latter version is not that easy these days, as sloping top tube have been the dominating design...

The measure from the center of a circle to its edge is the radius.