Well C rating is how a battery output is listed, C times the capacity, in your case 1.32 amps give you your packs constant available output. 13 x 1.32= 17.16 amps. Burst is rated same
17 x 1.32 = 22.44 amps. Now, that said, couple of things to throw at you, #1 don't always believe the C ratings mfgs put on their packs, many do not perform as stated. Rule of thumb I use is when selecting amp rating for a pack is to use the 80% rule. You motor should only draw 80% of the packs capabilities. So if your pack is good for 17 amps constant you should look to make your set up draw around 13.6 amps. Does two things, helps increase the pack life, as it's not being run at it's full ability, and two it also allows a little lee way in case the pack isn't quite up to snuff on the C rating.

Now then, on a brushless motor, the amp draw is the same no matter what position the throttle is in. Umm, the esc on a brushless set up is a basic on/ off switch. Firing each leg of the motor, for a specific length of time to give you your speed. Unlike a water faucet where the more you turn it open the more water that flows, a brushless set up is a wide open or off faucet. Folks get fooled into thinking the amp load drops when reading a meter. A meter averages the amp draw so other then at wide open throttle the delay between the esc firing causes the meter to be fooled into showing a lower amp reading. Wide open throttle is the reading to use for your amp spec. Also something else I just thought of on the 80% rule above. On most set ups, a prop unwinds slightly when the bird is in the air. What I mean by unwind is that the amp draw does in fact drop slightly, from what you read sitting on the ground running a static test. BUT, some props do the exact opposite, they pull even more then when sitting still. The extra 20% you allowed for in your calcs will keep you from blowing a pack if you run into a situation like this.

And if not to confuse you even more, a pack can only provide the amp draw specified on it for a set amount of time, before it gets to cut off voltage. Go below this and you will damage the pack. Going with a bigger capacity pack, will allow you to run longer, but adds weight.
I have a Slow Stick myself, I run a 3S2100 pack on mine, so mine has a bigger fuel tank, so to speak.

Here's an easy way to remember 2 things on packs, C rating is like the size of a water hose. Low C rated packs only allow a small dribble of water to run out, a higher C rated pack is like running a bigger diameter hose, more water flows.
On capacity, like your 1320 pack that would be a small water tank, a 2100 would be a larger tank, a 3700 would be an even larger tank.
C rating is the size of the hose, capacity is the size of the tank the hose is connected to.