Does bitcointalk Forum rank really matter 's for signature bounty campaigns and what are the links between "Merits" and "bitcointalk forum rank" ?
Well btctalk rank does matter if you are aiming to earn huge amount because high rank means high reward.
Due to the new system merits are now necessary to rank up, there's a corresponding merit for each rank you can learn more here:
https://bitcointalk.org/index.php?topic=2818350.0