You can easily measure the stem, from centre to centre. Also, measure your top tube length, centre to centre, since the 2 combine to give your reach.
If you play around with shorter stems and find one which is comfortable, you will be able to measure and replicate that position on other bikes. There is no useful formula or guide as to what is the "correct" reach, it depends on your flexibility, build and experience, and will probably change over time.
It is hard to measure angles on a bike,but they contribute towards things like the layback of the saddle. I like to measure the bike on a grid , in [x,y] with the origin [0,0] at the centre of the bottom bracket. Use a plumb-line to mark the BB position on the top tube, and measure back to the saddle nose, and forward to the bars, from this position. You can then be assured of duplicating the 3 points of contact (pedals, saddle, bars) whenever you need to.