At a guess, since Vis only gives a +1 per and gains a +2 from Puissant Ability, I would assume Cyclic Magic and Talisman Attunements do not affect them either.
Is this true or not?
That would be my take on it, as well; however, I don't see why there couldn't easily be a Supernatural Virtue that provides a cyclic bonus to a Supernatural Ability but Talisman Attunements seems too integrated with Hermetic theory. If you are creating a new magical tradition around a Supernatural Ability and want them to have a talisman-like item, I say, "go for it!. I think it sounds interesting. If you have HoH: Societates check out the Ex Misc. chapter.
The character in question is a Hermetic Sahir. I need to know if it applies to Sihr rolls.
Oh, that one's easy. They don't apply to both Hermetic magic and Sihr. Talisman bonuses are purely Hermetic, so never would. The Virtue is a trickier case, because you could argue that it's the nature of the magus's Gift, and thus should apply to all his Magic supernatural powers, but that's not how it's written. I'd probably allow it for a character who had taken both the Virtue and the Flaw, extending both, but probably not for someone with only the Virtue, but that, again, is an extension of the RAW. As written, you'd need a separate Virtue.