Until just recently, one of the only ways to use PowerShell to work with the Office 2007 Suite (Word and Excel  primarily) was via COM. Unfortunately, COM access can be relatively slow some times.
A new CodePlex project has just started up and is blogged on the PowerShell Team blog HERE.
Definitely looks promising.
1. Yes, one can use Excel to save a particular file as a CSV, then use the *-csv cmdlets to work with the data.