Pet buildsFollow

1) a) The dash/prowl combination would shine in PvP (where growl has no effect), and in instances where you expect the group to have good aggro management on their own. However, if the healer pulls aggro or the cat is intended to be used as CC...growl is necessary and the group might call you a huntard and boot you.
b) You can't do anything about focus regeneration or reserves inside the pet build. What you can do is go to beast mastery and get Beastial Discipline (doubles focus regeneration) and/or put 12 points into marks to get Go For the Throat - 50 focus every time you crit.
c) I haven't done the math for cats, but I can still garuntee that for sustained DPS cats are at least the 4th best, not the best. The most sustained DPS will be from scorpids (in long fights scorpid poison will do more than any other pet ability), the second most is from wind serpents, and the third highest DPS is from ravagers. With a ravager you can do growl/bite/dash/gore, and while you dont get the damage bonus of prowl it will still get to the target faster (making up for it) and gore will do more than claw. They have the same tooltip DPS as cats. But I would go with a wind serpent or a scorpid...keep in mind that if you have GFtT + BD, you get 3 LB's in the first 4 seconds, plus 1 more every 4 seconds and every time you crit.

Actually you have it backwards, claw is high focus. While bite is 35 and claw is 25, claw can be used every 1.5 seconds, while bite only every 10. Meaning bite and growl will never burn more than 50 focus, but claw can go through 100 in 6 seconds.

Claw has the advantage of doing more damage over a short period of time. This is why I would recommend a gore pet or a wind serpent - gore has more sustained damage than claw, and lightning breath (while costing double) has more than double the damage of either. While intimidation is good for drawing aggro, intimidation + growl is even better. This is another reason I would really recommend a ravager if you can get one - if you dont have prowl, its like a more-powerful cat. And since it can only have the 4 skills (we wont count cower) you dont have to pick and choose.

if you want pure damage, there are better pets then cats.
i believe scorpids could pump out the most sustained dps, followed by windserpents.

For a twink, it's either a wind serpent or a boar. Past 30 I'd say a cat will do too.

The four basic things to PvP - survivability, burst damage, movement, and surprise. Survivability isn't an issue for pets, as they're mostly ignored.
Boar: Charge is a great PvP tool, as it both gives your pet speed and immobilizes the target for 1 second. It also has great burst damage.
Wind Serpent: If rooted, LB can hit 20 yards. There's no deadzone on it. LB also has great burst damage potential, especial with GFtT if you crit.
Cat: Prowl for the surprise.

My baseline is the rank 2 resistances in everything. If it's important, a rank 3. Rank 2s are only 15 points each - that's pretty cheap. After that... split between stamina and armour as you see fit.

There are 2 ravagers on azuremyst. One will be untamable next patch. The other will still be tamable. So in azuremyst and bloodmyst you have one ravager per island. They make great DPSers IMO, 3rd best (but more instant than scorpids).