The SW d6 2nd ed. RAW (in my reading :)) says, under "Lightsaber combat" (p.151) that a Jedi may use lightsaber combat to parry blaster bolts. (Bold emphasis mine.)
From this it seems to follow that you can parry any weapon that shoots blaster bolts, ie. has and is firing at you some kind of blasters.
I'd allow parrying the shots of the Scout Walker, but none of the other examples you listed, since those aren't using blasters for the firing: they use laser cannons etc.
Sure, blaster is not too strictly defined in the SW lore (afaik, but I may be wrong) - however, for a RAW answer, I'd go for the above. A weapon that explicitly has "blaster" in its name can be parried. Others that don't, simply can't be.