Uhm, I wouldn't be so optimistic about recharging with foreign credit cards, but you can give it a try!
At the airport it's more likely to find an English speaking dealer, that's sure, BTW that shouldn't be a big problem in any case: Sicilian people are so friendly and will do their best to help you also if they don't speak much English!
With Wind you can renew the option before the 30 days, just send an SMS to 4033 writing RINNOVA SI.
Wind would be better since it's cheaper and gives you more data than TIM.