I guess it really depends on when your next assessments are for your second term(i.e. next year) are your assessments at the start or are they spread throughout the term... although a lot of people could argue that there is a correlation between the efficiency of your study time and your ATAR rather than the amount of study you do, there are a lot of variables that could influence a correct estimation of the study time you need-i.e. whether you plan to revise or study ahead during the six weeks, how far ahead, if you are already ahead, are you for each of your subjects, what is your attention span, what kind of a learner are you?, I think the realistic amount of time to study is best answered by thinking about the various variables and deducing an answer yourself...
Much as it would be a lovely experience on exchange and no doubt sharpen your French skills on a daily basis, but you need to bear in mind that you also need to practice writing component as well, which will take extra study time, and French overall forms only less than 1/3 of your total units counted for the HSC, so I doubt one hour per day is going to cut it, if you don't have time, it would be better to find at least 2-3 days free in each week devoted mainly for studying and you may choose to have fun in the evening-rather than doing 1 hour each night... after all, this is your HSC year and everyone will have the same amount of time-and you need to use yours as efficiently as possible, have some fun, but remember, the notion of 'holidays' does not exactly exist for HSC year-it signifies self-discipline rather than relaxation
Do as much study as you can while meeting all your other commitments and desires-I suggest you make a very detailed timetable and stick to it-it also depends on how determined you are to get that 98 if it could potentially mean you might have to sacrifice some of your 'exploring' time to study-but do what works for you-and I wish you a wonderful trip (and don't forget to study hard
) best wishes