For Kreuz/Chrüüzli, I do feel there might be a semantic difference. The one we do on a form is not a christian cross or Swiss cross version. In that sense, I find natural to make a difference spontaniously too. One says equaly in high German sein Kreuz or sein Kreuzchen setzen.
But I admit I call this Chrüüzli just Kreuz in High german. Perhaps I am seeing references that don't exist (die nicht vorhanden sind).
I think in this case there's nothing more behind than the straightforward meaning. But to me it seems that the diminutivs are far more often used in the Eastern part of the country than in Bern, Fribourg or the Wallis. In Bern we'd definitely say "achrüze". Anyway one thing is for sure: No Swiss would ever call the "Franken" a "Fränkli".
Personally I think the "Li-itis" is about as bad as to end every second sentence with "oder".
Ja, sich durchschlagen. Swiss German usually has kept the short versions, like Dutch and Danish, the Germans reintroduced the normalized long form. As always, long /o:/in Basel, long closed /a:/ in Mittelland. Think of it wenn you have a very short verb, with a bit of luck, you might find out yourself.