Will seals still yield their power if tattood rather than engraved

Depends. If the one doing the tattooing is a competent occultist and able to channel the energies that would ordinarily be present in the engraved materials, then yes. Otherwise, no. It's not just the one thing that comprises the seal. Just like the ingredients for a hamburger isn't just "hamburger".

hahahaha, no

If you consecrate it, I don't see why not. Treat it like a sacred symbol tho. Don't tattoo on your feet or hands, for example, as they more exposed to dirt.