1) Depends. Its just another scan tool. It can be usefull to pull codes for yourself and along with other tools DIY some of the easier repairs that will come along. Its also important to use a scan tool along side the cardboard radiator block (see the link below for the precautions).
2) Then its working.

Didn't see the normal winter MPG losses did you

Read the original thread
here. For the potential best MPG performance in cool weather you'll also need the hot intake air mod.
HTH!