nigel, I'll take a shot at your questions. Keep in mind my opinions are my observations of my wife and what I've retained from what doctors have said and what I've learned from others through the years. Others may disagree.
"Stretching & Muscle tensing"
This is a sign of RSD however nerve damage I think could cause this also.
"Ice (prefer warmth over cold)"
If you are referring to placing ice packs, heating pads on sore areas this is not something that is advised to apply to RSD injured areas and nerve damaged areas. I've heard in most cases do not do this especially ice packs, however I've heard some have had little relief doing this but not many at all.
"Lying-Walking"
Those with RSD suffer all the time whether it be laying down or walking.
"Any poition out of a seated position with my knees at 90 degrees comfortably"
Now, this is where I think you may have trapped nerve issues not RSD. My wife never experienced any relief at all positioning limbs with significant relief. I've never read any RSD info pertaining to this.
"Car rides (althogh im sitting down, my knee is not relaxed at 90 dergrees relaxed. insted the position makes me feel like im stepping on a frying pan!)"
My wife doesn't like riding in vehicles because of the bumps the cars takes. It's not the sitting position so much as bumps in the road or taking corners, even though we own a large Cadillac. Even the stress of traffic will trigger my wife's RSD pain more so than the bumps even though I'm the driver.
"Doctors manipulation (pain reaction the follwoing night)"
My observations are manipulation of RSD areas trigger immediate pain-flares that may last days.
"1. Does the pain in the particular limb aggravate in certain positions (eg when extended) and calm down in more comfortable positions?"
I would say no.
"Does the discoloration in the affected limb go once elevated or when mobilizing the limb?"
In my wife's case, no.
"3. Is its possible to have RSD and not have abnormal swelling in the area?"
Yes. My wife's legs swelled from RSD around 2-3 years after she broke her wrist in which caused her RSD.
"4. Is it possible for some symptoms (eg motty patches, redness and abnormal heating) to travel to the other leg, however not experience alot of pain in it?"
In my wife's case yes, the RSD can spread, even though many doctors think it doesn't, It absolutely does, however so does severe pain!
"5. Is it normal for the affected limb to jump/tick when trying to fall asleep?"
Yes, I've seen this with my wife, but my hunch is so could other conditions cause this especially nerve issues.
nigel, there are some doctors here in the States who think that one with RSD must show all signs of the disease in order to make a diagnoses, if not one does not have RSD, however this is false, most people with RSD do not show all signs of the disease at the same time if ever. Different signs of RSD pop up during different stages of the disease through the years. Also, there are doctors who think RSD does not spread. This is also false, it does spread for many, for the minority no, for most--yes. I hope this helps and good luck in Germany!!

jim&suzy