Question: Ok, long story short, I'm currious how long it would take an agency to crack a 10-15 character winrar password. The file names in the archive are also scrambled including a word at the start and numbers and characters. Roughly, should I have reason to believe this could be cracked within a reasonable time frame?

Answer: 
There is some data [here](http://www.tomshardware.com/reviews/password-recovery-gpu,2945-8.html). WinRAR uses a custom [key derivation function](http://en.wikipedia.org/wiki/Key_derivation_function) which involves thousands of SHA-1 invocations. Apparently, with two good GPU, about 15000 passwords per second can be tried.

Then it depends, not on the *length* of your password, but on the way you produced it. It's not the length which makes the password strong, but the randomness. If your password is a sequence of 15 random characters, chosen uniformly and independently of each other, then it will resist forever. If it is a common English word which happens to be 15 characters long, then it is toast and will be recovered in a matter of seconds.
As mentioned rar uses SHA-1 which is pretty strong. You can have a good comparison of different algorithms [here](http://www.gat3way.eu/index.php?mact=News,cntnt01,detail,0&cntnt01articleid=192&cntnt01returnid=15).
As you can see cracking rar is slower than WPA-PSK.