I remember we switched from Ayonae.Ro to Ayonae.Com for some reason, though I can't remember what it is.

A client of mine has a really clever domain name using the .IT, but I don't want them to get married to that only to end up screwing themselves later. Are using those foreign domains for a US commercial product a bad idea?

Depends entirely on the registrar for that tld. Numerous domains like cx and tv sell them out since their own usage is minimal.

Depends 100% on the TLD. Some, like .sa and .ly, arbitrarily impose their own societal norms on the use of the domains they sell. So, if you're being too much of an infidel, they've been known to yank it out from underneath you with no warning (on the other hand, bit.ly is probably the gateway to as much porn as any domain that exists; they must bribe well).

Italy is 100% fine, to my knowledge. I don't know of a single case of them being any more fickle than the American TLDs.

In terms of SEO, using a foreign domain like .it can signal Google that your content is less relevant to searches on google.com (and more relevant to searches on google.it). For a small site, that can be significant enough to pay attention to. For a site that isn't dependent on search traffic or intends to do lots of linkbuilding, marketing, etc, it doesn't really matter enough to worry about.