A Q of .5 is better--lower tighter. .707 is maximally flat and more common. Its maximmaly flat because its the highest you can go without getting any resnonat peaks and getting the most hz extensions. Higher Q are less accurate. To get the Q lower the box volume has to go alot bigger. "It [Q] represents the degree to which the electrical, mechanical, and pneumatic circuits of the woofer/box combination interact to control resonances."
"and is it obtainable in port designs?"
Yes, its one of many things one designs around.
"and is it obtainable in port designs?"
Yes, its one of many things one designs around.