Does this get ink stains out of clothing?

The best way to get ink out of clothing is cheap hair spray.

Can K2R be used on a 100% polyester tablecloth?

Yes. I'm quite sure K2r will not damage polyester. It's best for greasy stains and can be used on fabrics as delicate a silk. I think the only way to damage polyester is with fire! LOL! Best wishes!

Is this a good substitute for the old trichloroethane, perchloroethylene, petroleum hydrocarbons spot removers that have been banned since 2000?

This spray removes oil stains perfectly. I have used it for years. My sister used it on one of her husband’s shirts and couldn’t believe that it took the stain out completely.

Does this work on clothing? - silk, cotton, others?

Works GREAT on silk, particularly ties. OK on Cotton, as well. This is a solvent product that does best on oily/greasy stains. If you drop something greasy, like salad dressing on tie, jacket or trousers, it's the best thing going. Doesn't do terrifically well on milk-based stains, but it does remove the grease component.