"One of the answers I'm looking for is were all coil stamps printed the same way ie with the same number of perforations.
Perforations are measured not counted.
Perf number and number of perfs are two entirely different things.
Coils & booklets were issued with a variety of different configurations of perforations.
Sheet stamps are the regular issues.....perfed on all four sides, although some were scissor cut from sheets and can have one, two or even three cut sides. These usually look like sloppy cuts, not square or parallel.
Sheet stamp #720 perf (type) 11 x 10 1/2 (same Washington as below)
On the sheet stamp 11 x 10 1/2 means that the top & bottom are perf (type) 11.....the sides are perf (type) 10 1/2 (all sheet stamps with a compound perf are described this way)
Typical horizontal & vertical coils....
Horizontal stamps, vertical perfs....#721 perf (type) 10
Vertical stamps, horizontal perfs.....#722 perf (type) 10
On album pages.....when there is no perf type mentioned but it is noted as a coil or booklet, look back a page or two to look for the last perf type mentioned, it follows until a new perf note is necessary.
Using your perf tool thing......a perf guage.
Be very careful to align perforations on your perf gauge exactly.