Since you asked, I'd say that Rose Quartz is about as good as she can . Building a brick on 500 points is hard. She takes damage very well, but I wouldn't get too carried away imagining feats of strength. Your upper limit is throwing a motorcycle, and that would do less significantly less damage than throwing a more reasonably sized projectile.
You're generally right about Strikers being different from ordinary limbs, but Martial Arts specifies that you can treat your limbs as Strikers with a -20% limitation. Still, Long Talons work just as well. Remember that because Rose Quartz is SM+1 they get Reach C, 1.
As a rule, weight is a feature in GURPS. I took a look at the issue on the gurps forums, and the general consensus seemed to be "take extra HP to reflect that weight". In Rose's case, using the damage to objects rules (B483) to calculate that.
I'm sure you don't want to hear me suggest you need another Injury Tolerance, but Homogeneous doesn't appear to include the benefits of No Blood, which you may want.