"Should Talk Board Members be required to make a statement of how many nights per year they actually are gone from home on travel? Maybe for future elections this could be a requisite?"

No and no.

"Does the 'general member' have anyway of knowing that the TB members really travel?"

No.

"Should there be a minimum requirement? 100 nights per year or so?"

No and no.

Here it's enough for me that the members of FT who've voted have voted for a TB member. If the FT membership base wanted to screen out certain candidates, these very same general members of FT can exercise their judgment and choose not to vote for those who don't meet their criteria.