I have heard this before so let me give you my answer when you say you want a HORSE strategy guide: There isn't one. HORSE is not one game, it is 5 seperate games each with thier own different rules, winning hands, antes, blinds... Everything is different about each game. There is no HORSE strategy guide. There is no smooth transition directly from NL Hold Em to HORSE. Limit Hold em, Omaha Hi/Lo, Razz, Stud, and Stud Hi/Lo are all completely different games, each with its own completely different set of nuances and strategies.

The only way to learn HORSE is to spend time on each game individually. If you go straight from NL Hold em to HORSE you are going to have incredibly large leaks in the other games being played as each game is different. I did notice in your post you said "the Omaha game had 6 to the flop" and that caused you to tighten up. No offence but this shows you need to spend a lot of time learning Omaha as 6 to a flop is practically a dream game for O8.

Basically you are not going to win @ HORSE for any extended amount of time if you are not taking the time to learn each game individualy. I just can't stress this enough. HORSE is simply a cool acronym for many games, but you are not going to excel at HORSE unless you can break each game down and play each and every game right.

It takes a long time to learn them all but until you get there I suggest concentrating on one game, get it down, and if you want to learn another. Eventually you will get there.