I use a 3/4 impact wrech to take them apart. They are very tight and usualy have loctite on them.
Of the ones I've done, all have have regular threads. I've never seen one with reverse threads, but don't know for sure if that's true for all of them. I don't know why it would have reverse threads, there doesn't seem to be any reason for it that I know of.
One thing you might try to do is find a cylinder repair shop. I have both a Case and New Holland tractor that I've rebuilt half the cylinders on, and will probably rebuild the other half in time. My dealer sells kits to rebuild the cylinders that include all sorts of extras that you don't need. They have also started to upgrade there pistons and require new ones to fit there rebuild kits. Even if the old piston is in perfect condition, and they usually are, they make you buy a new piston. Some are as much as $200 each!!!!
Luckily I've made friends with the guy at the parts counter and he told me about a local guy who they use when they need help with a cylinder. He sells just the parts you need, and has the seals for older pistons that the dealer no longer carries.
A rebuild kit costs around $40 to $60, plus if you have buy a new piston, that can run from $100 to $200 each. He sells the seals for $5 to $25 to rebuild the entire cylinder!!!!!!! His price per seal is more then the dealer, but since you only buy exactly what you need, it's much, much cheaper.
It's well worth your time to find a rebuild shop if you have one in your area. Ask your parts guy, or talk to the mechanics at the dealer, and see if they will tell you who they use when they have to send out a cylinder. The dealer never does it all, and for just about everything, they have contacts that will do it for them.
Good luck,
Eddie