Greetings Dario: BOTH lenses and bodies should be stored in the cocked position for a number of reasons. As mentioned, Ernst W. who literally wrote the book on Blads, recommends it, David Odess at
http://www.david-odess.com is a certified HB repair tech., and also recommends it as do other techs at the service center in NJ. Another reason is that if one is cocked and the other isn't and you inadvertently try to jam or force feed the lens to the camera, you can easily end up doing about $300 bucks worth of damage to both the lens and the body. BTW, even if both are tripped, shutter and lens, you still can't attach them unless both are cocked. Again, don't attempt to remove a lens which isn't cocked (look at the lens iris to determine that) or from a body that isn't cocked. That's really important with these cameras.
As for releasing the body, you can do it with or without the lens, just by tripping the shutter release. Just make sure to advance or recock the shutter afterwards. And note, tripping the shutter itself is NOT the same as hitting the mirror pre-release, which is located under the film advance knob or crank (push up). To trip the shutter in prerelease mode, you need to push the shutter release. You don't need a mag or a lens on it. Nor do you need to store it with a lens. Front and rear body caps are available for around $5-10 each from
Dead Link Removed. (used). Lens caps, if you need them, are also available.
Meanwhile, welcome to the party !
Mark