First, welcome on this great board of steady knowledge. Let's see if we can assist you in getting better shots!
Second, are you left or right handed? (i mean, do you write with right or left hand?)
I'm right handed, so in my case i operate almost always regular (sled on the left side of the body).
Right hand controls the handle, the left hand controls the gimbal. It was almost directly second nature to gentle touch the gimbal with my left hand.
1) I know that the gimbal hand should touch the post very slightly, so I do. (like i did on the Glidecam)
But what about the other hand? Should it touch the gimbal handle also just slightly or is it better to hold it more stronger, to avoid transferring steps to the sled?
Well, you are right.. your operating hand which moves the sled in all dimensions needs only a gentle touch/light grip. How bigger the rig aka how heavier the load, it is 'normal' to have a bit more tighter grip on the gimbal. How lighter and smaller the rig, a really soft touch is enough. If you learn to manage it on a smaller rig, you find it easier in the future to operate a bigger rig.
A normal grip on the handle is fine, this hand will guide the sled horizontal from left to the right (vice versa) and also for pushing the arm down and 'pulling' the arm up. A really tight grip is not needed.
2) All the basic sled stabilization should be done by my body.
So if I walked down a line (missionary), touching the gimbal+handle with my hands is not necessary - is that right?
The hands are just for directing and lifting the sled, but only if needed?
Not really, always have both your hands on the Sled at all times to operate the system in any direction you want. With no hands can be a 'trick' to see if you really
setup your arm/vest connection right. It is possible if all is tuned fine to even walk arround your own sled. If you stand still, with a good posture the rig should
float in space besides of at front of you. But be carefull at all times! EDIT: when running use your operating hand on the gimbal and stretsch your gimbal hand/arm a bit horizontal like your are a bird to keep balance at speed. Ofcourse the help from a assistent would be even more save !!!
3) The Zephyr operation manual tells me to setup the arms about 5-10° up horizontal.
But what about the weight with e.g. Alexa? Would it be better if I set the arm down for less stiffness with the heavy Alexa?
What is the best arm setup for slow following/walking shots?
Besides tuning your arm knobs for the weight, it is also a way to achieve a certain 'eye' level of your lens. I like my arm a little bit below horizontal for slow walking
and running. But most of the time this is a personal preference.
4) The Zephyr operation manual tells me to set the side crews on the arm socket differently on the top and bottom.
If I just turned the bottom screw all the way in and leave the upper screw a bit out, is the arm&sled&cam still secure?
What about the rollers, how should they be set for using an Alexa/16lbs? All in or out?
(Maybe there is an experienced operator, who can tell me this in german, the operation manual is really written dizzily in this point...)
The settings are 100% important to achieve and remain a good posture, it has also a lot to do with your body size aka big or no big stomach for example :)
Just play arround with the 4 settings without putting the sled on. Adjust them so that your arm is floating 'free' at front of you in stead of moving
from you when you let it go or the other way .. (in your face!) so be carefull when trying this!
5) If somebody knows: Is there a hot swap available with the Alexa by using the small dove tail (V-Mount)? If yes, how to plug??
What is the 1/2 switch for?
As far as i know, the Zephyr is 12V only, the switch is for use 1 or 2 batts at the same time. Both plug in below at the back side of the sled.
Besides that, a battery straight below the post is also nice to achieve a good balance. Be carefull, i have no idea how good the cabling is inside
the sled for powering a Alexa.
Can you show some pictures of your setup and maybe some video of your issue's?