Look in your gauges folder for Cessna182rg.gau. It's probably missing but you can extract it from one of the .cab files on CD1. Sorry, I can't help with the addons except to suggest you look at the panel.cfg files and make sure the gauges referenced in there are in the gauges folder.
There is a utility that will check for missing gauges here
http://www.fsgauges.com/ It's not perfect. It won't detect .xml gauges so it will tell you that they are missing. You will just have to look for them manually.