Can you fly a SID or STAR without ATC surveillance? The AIP ENR references are very ATC heavy.
Yes, but as stated earlier the SID/STAR will only provide terrain clearance. Traffic clearance can not be assured as the design requires to be used in conjunction with a particular configuration of runways, airspace and so on. The easiest way to explain that is that other aircraft need not be on the SID/STAR procedures at all and could just be direct tracking so they are in no way compliant with the SID/STAR traffic altitudes. So without ATC traffic could be anywhere they want to be and you need to have good SA to separate when following random STAR/SIDs that the traffic may have no awareness of. Telling someone that you are 7 GPS to run UPBUM when the departing aircraft is 5 to run POOBA is really not going to be easy to resolve.
Also RADAR SIDs do not afford any terrain clearance on reaching the vector height, you obviously need ATC on these as you will still be below MSA as the altitude is predicated on MVA and vectors to remain terrain clear until MSA.
Are you sure? JEPPs is very specific that a clearance to operate in a restricted area is given in the same form as a controlled airspace clearance.
Depends who has issued the clearance or approval. When you are a Civvy operating missions within military restricted airspace you usually get approval from the authority that controls the restricted zone, say when target towing etc... The overlaying ATC will just query if you have approval to do so, then you just communicate with the guys shooting at you.