how to check if given pool exists using IControl

We never included "exists" methods to the APIs. The procedures you listed are the ways to go and it depends on the size of your configuration and or how much processing you want to do. You can either get a list of pools and look for a match, or perform a get_* on your pool name and look for a SOAP exception. get_description() is probably a good one to use. Unfortunately all of the error codes are not fully documented so you'll have to test it out and use the returned error string as a match. The error returned for object not found will be the same moving forward.

-Joe