For a local bank account we found the best option was to open an international account with lloyds in the channel islands. You can have easy online access Euro, GBP and USD accounts all linked to VISA debit cards in each currency. Best thing is you then have an IBAN number for interntaional (wholesale FX rate not crappy retail rate) transfers from your aussie bank, and an account for bigger ticket item payments like winter haul out
If you keep a miniimum amount in one of the currencies there are no fees either even for cash advances from an ATM.
On the Schengen issues we overstayed and had no problems but had to field a few questions from immigration officials so best to have an explanation ready such as weather hold ups, maintenance
issues etc. Ive been told you will get more leniency from maritime immigration as they understand the issues better than if you try and reenter via airport
for example where they are far more suspicious.
Movement between france spain
by boat was not checked in our experience with the onus on the skipper
to find not always present immigration at ports
of entry if you wanted to bother.
Discovery of overstay on clearing out wasnt in issue for us ie we were clearly leaving anyway and so common sense prevailed.
The issue may come up when you are past or close to your 90 days and trying to enter your next country so try and time your trip so that your not doing that. Also try and visit at least one non schengen country during those 90 days so actual days would need to be counted out in detail and only one official actually bothered to do that in our experience (but since that was on clearing out we got a "finger wave" and that was it).
At the end of the day your clearly not a refugee, have your own means of transport and appear well funded so common sense prevails at least around the ports
. Not saying you wont get an officious type that causes problems but that didnt happen to us or any other non EUs we spoke to so you would have to be unlucky in the western med at least.