Now that's an interesting WI with the tanking....
I would expect them to pursue the tanker option, yes. The F-104 didn't have a fantastic range, and Australia is a fair-ish size - ......
It depends on how they do it. The RN had a pair if Buccaneer more or less permanently configured as 'maxi' tankers on each carrier, with bulged bomb bay tank and slipper tank on the wing. If the RAAF does something similar and each squadron had a couple or the wing has a small flight of permanently configured buddy tankers then I think they'd get plenty of work and the planners would be asking for a more robust capability.
any chance of earlier AEWC?
Air Forces were strangely averse to AEW in the 50s and 60s, unlike Navies. The RAF undertook trials in the 50s with Neptunes but didn't pursue it and the USAF only got about 42 of the 232 EC121s built. I doubt the RAAF will forge its own path.
Also I wonder if the RAAF deploy Starfighters to Rolling Thunder?
I doubt it, it's probably not very well suited and would likely follow a similar in-service trajectory to the Mirage although the US wouldn't put pressure on the supply chain like the French did.
The Vigilante is another thing entirely, it was to enter service from 1966 and given the maturity of the platform i'd suggest that's realistic. When the Government goes looking for a RAAF combat commitment to Vietnam in 1967 there would be 2 Vigilante squadrons in service and most of the Canberras would be gone and their crews converted. This means the historical situation where an excess Canberra sqn was shunted to Vietnam would not occur, so a red hot Vigilante sqn would be sent instead. I don't know if it would be used in Rolling Thunder, its a bit capable to be wasted on CAS in South Vietnam and one reason the Canberra was relegated to that role was because it wasn't capable enough to deal with the AAA and SAMs up north.
...if they're thinking of using it in the maritime strike role, that area gets even bigger.
Maritime strike was a very low priority for the RAAF until the 80s, the Melbourne's Skyhawks took care of that. The Mirages and presumably the F104s would be half in a Fighter configuration and the other half in Attack configuration, with each type having a different flying programme as a result.