Nostalrius Begins - Quality wow vanilla realm (1.12)

So..how many ranks can you go up at once?

It depends on your current rank.

In ranks 1-5 it's pretty easy to earn two ranks a week.
By rank 8 you're getting at most one rank per week.
By rank 12, you're getting maybe half a rank a week.

but there isnt a cap on how many?

drahy wrote:but there isnt a cap on how many?

It all depends on your current rank before honor calculation is being done.
The maximum amount of ranks you can do in 1 week is 4 (technically 3 since rank 1 is not based on honor amount or ranking points, but about 15 kills). as rank2 requires 2000 RP, rank3 requires 5000 RP and rank4 requires 10000 RP and the maximum RP you can get in a week (with standing 1) is 13000.
This means that if someone gets standing 1 one week and did not have a PvP rank from before, he/she will go to 60% rank4.

http://www.wowwiki.com/Honor_System_(pre-2.0)

"... there is a rank promotion limit, which is due to the fact that you simply cannot earn more than a certain amount total rank each week, plus your total rank decays by 20% each week. A rank 0 (pre-private) can earn at most 13000 RP, which would put him in the middle of rank 4. A rank 5 (with the minimum 15000 RP) can also earn 13000 RP but will lose 3000 RP to decay, so his new rank will be barely 7 (25000 RP)."

"There is also a rank cap based on your experience level. Characters under level 30 cannot advance past Rank 3 (with 6500 RP). "

Once RR13 can I use my RR13 gear forever or only as long as I'm RR13?

You only need the rank to buy the gear. You can equip and unequip it after it has been bought.