If you only have one tire and it will be the only set you have, skip the HTLR and get the vulcanized material. It will hold air better and give a little more dependability. The X-one is definitely more aggressive and I would call the grifo a lighter intermediate tire.
Yes.
You’re not gonna be disadvantaged from an intermediate tire, trust me. Gravel bike geometry will only be slightly a hindrance, but not once you learn to corner on it and when/where you can pedal. So yes, get the more aggressive intermediate tire and give it hell. Or if it’ll keep you up at night, get an aggressive tread up front and less in the rear - MTB style.