If a bowler's front foot lands on the line and some part of the foot is outside the line and some part of the foot is on the line but no part of the foot is behind the line, is it a fair delivery?
The way you describe it, its a no ball. To be a legitimate delivery some part of the foot whether raised or grounded must be behind the popping crease No Ball.
Here's what the official Laws of Cricket documentation by the MCC says on no-balls:
the bowler’s front foot must land with some part of the foot, whether grounded or raised
I don't see how what you're saying is physically possible. Even if some part of his foot is behind the line, whether on the ground or in the air, it's a fair delivery. The alternative to that would be a player having his entire foot directly above the line, which doesn't sound like a plausible situation to me.
21.5 Fair delivery – the feet For a delivery to be fair in respect of the feet, in the delivery stride
21.5.1 the bowler’s back foot must land within and not touching the return crease appertaining to his/her stated mode of delivery.
21.5.2 the bowler’s front foot must land with some part of the foot, whether grounded or raised - on the same side of the imaginary line joining the two middle stumps as the return crease described in
21.5.1, and - behind the popping crease. If the bowler’s end umpire is not satisfied that all of these three conditions have been met, he/she shall call and signal No ball. See Law 41.8 (Bowling of deliberate front foot No ball).