Chris is correct that the red galero is the only one that actually had some existence in reality. The hat would be given to each new cardinal by the pope, but this was discontinued by Paul VI in 1969. In heraldry, the number of tassels varied a lot. Italian usage, though not uniform, called for fewer tassels than what we are accustomed to now. It was the French heraldic tradition to use 15. The only real galeros I've seen were from a distance because they're hanging from the ceiling of the Cathedral Basilica of St. Louis. As much as I stare at them, I can't make out 15, so I wonder if the real ITALIAN hats ever had 15... but I'm more than happy to be corrected by someone whose closely examined one.
The development of the green galero was driven by the creation of patriarchs in the 1400s. Prior to that there were cardinals, with their arms adorned with red hats, and bishops with their arms adorned with miters. This group new needed something to distinguish them, hence a green hat... green taken from the color of bishops and the hat from cardinals. Again it took some time for the number to tassels to be solidified but eventually the French usage won out. One must recall that throughout most of its development, the color of the galero was more important than the number of tassels, which explains why it was only the 1800s that the tassels were set. It was Napoleon who settled French usage (though he basically lifted in full the eccl. heraldic practice of l'Ancien Regime) and although the Holy See despised Napoleon, his system was too sound to disregard. In 1832, the Holy See settled the number of tassels for the higher ranks of clergy.
The practice of bishops adorning their arms with miters was not very popular in France or Italy; from early on the galero alone was used exclusively . The Germans held out much longer. Most German bishops were also secular rulers and had much more exalted secular titles to display heraldicly with crowns along side miters. The English Church due to its separation from Rome froze medieval practice, and so never picked up the green galero. It was only by the Earl Marshall's warrant of 1967 that the galero entered English heraldry for Roman Catholic arms, and in 1976 for minor clerics of the Church of England.
I think it's pretty clear that the Lord Lyon and the Earl Marshall both basically modeled a system of eccl. hats for their churches off of the Catholic Church. I'll give the Lord Lyon points for creativity for choosing the Geneva bonnet, but I don't think one can honestly say that Scottish or English heraldic tradition supported a system of eccl. hats in the way that Catholic heraldic tradition has for centuries. So, basically, I agree with Michael's statement. All this leaves you is an exercise in comparing and contrasting the Anglican and Presbyterian Scottish system of hats with the Catholic one rather than a meaningful reflection on the development of those hats in those Protestant churches.
Incidentally, while were talking about the development of Catholic arms, the "cutting edge" right now is with Anglican communities returning to the Catholic Church under the separate structure of Anglican Ordinariate, which Benedict XVI established. This isn't dramatic development, don't get me wrong. The current system is robust enough to incorporate these new structures with just minor tweaks. Still it's interesting to observe.http://www.theanglocatholic.com/2011/02 ... inariates/https://ordinariateexpats.wordpress.com ... /heraldry/