I dont worry about ethanol, all my fuel hoses are new. On older cars a bit more, complex and difficult to work on, ethanol can be a bigger issue. I think as far as Alfas fuel system, the Fispa fuel pressure regulator is the only older part than can be broken down over time by ethanol, the rubber diaphragm inside. BUT I am not an expert on the subject and many Alfas have had this replaced or the later gen's that didnt have Fispa regs at all.
As far as octane, my 74 spider will run on lower octane, but doesn't seem to like it a whole lot. I put "regular" in when I first got my car running again, and it ran and started up okay, but it wasn't the same as running on "premium".
Just my .02$
Silver 1974 Spider- Weber 40DCOE151 carbs, BWA Wheels, 80K original miles 2014 Blue Honda Accord, automatic, 4cyl