Beholder vs Ghoul

In short, the answer is "no" to both.

The Ghoul's scavenge ability (their graveyard visit) isn't classed as an intel role so would give no result to the Beholder if they were checked.

The role check / stalk abilities that the Ghoul has are currently implemented as inner abilities on the Ghoul role and don't "bubble up" to be exposed on the Ghoul itself, so they get a positive Witchcraft status if they hold a magic check, for example. Although this sort of behaviour has been mentioned a few times by players and may possibly change in the future.