2) Normally that is MORE then adequate to cool down engine after driving but I'm not sure what you mean by "cool down the intercooler"... Air cools the intercooler so idling wouldn't really help that.
3) It's most likely normal. If it really worries you, get some one else to observe it (like a dealer-tech).
4) I don't 'know' about this one but I highly doubt you will do serious damage by shifting at low rpms once in a while. You'll just have a less then exhilarating driving experience, if it is done regularly.
5) Read & follow the manual. Perform all maintenance properly and as scheduled.