I'll basically answer the questions in the order you asked them in:
1.I highly doubt that the majority of lecturers at Monash are difficult to understand, even within the commerce faculty, there are many students studying commerce related degrees there, so it would be really problematic if that was the case. Anecdotally my lecturer for a first year Economics subject at Melbourne was difficult to understand (both the way she explained things and her accent), but I am sure that I am sure this isn’t representative of the Commerce faculty. From personal experience, most lecturers are difficult to engage with, like in terms of asking for help and the like (I don't think it would be too different to Monash). Depending of on how you judge ‘better lecturers’, teaching quality is difficult to know but the Melbourne business faculty tends to hire many lecturers from high-ranking US universities, to make them a better research uni and improve prestige.
2.Melbourne doesn’t force you to do internships, development programmes or an IBL equivalent, but naturally the business department (and almost all the students are really keen and proactive about these things) encourages students to pursue these kind of opportunities. They have networks with many top companies/firms as a result of active student recruitment, graduates that work there and because Melbourne University in very conveniently located.
3.Melbourne University has a greater variety of exchange partners (both in terms of prestigious universities as well as more exotic countries). They also have partnerships with top business schools (would be naturally competitive) like Bocconi in Milan, Wharton in Upenn, University of Southern California, University of Virginia, Carnegie Mellon (for computer science) and UC Berkeley.
4.All the scholarships that aren’t Chancellors are based on disadvantage (which are also competitive). Monash uni offers far more scholarships based on academic performance (as well as Commerce specific scholarships). Don’t let this deter you, because unless the scholarship is major (like a half scholarship), HECs and CSP makes university accessible (at least for undergrad).
5.There would be opportunities to pursue a sport at a recreational or lower division competitive level. The top divisions would naturally be fairly elite.
6.There’s actually less students at Unimelb compared to Monash. Leadership in student clubs and societies tend to be a chilled and laidback affair compared to school (where you usually have to deal with the biasness of teachers and be judged by many more students). It tends to be an internal process where you get involved in the club for a bit, get to know people and run for a leadership position. There are also many great clubs and societies at Melbourne.
7.Within Australia, there wouldn’t be any difference, but internationally Melbourne would be more well- known because they tend to hire more faculty members from high-ranking international universities. I also think that Unimelb Commerce is more highly regarded internationally, because they have a very strong Economics department/program, and many multinational companies tend to hire Economics majors (since most Ivy League/MIT/Stanford/Oxford/Cambridge offer Economics degrees and majors, rather than Business/marketing/management/finance degrees at an undergrad level). That’s not to say that Monash isn’t highly regarded internationally, I know law students from there who has continued master studies at high-ranking law departments.
8.Not too much, an hour doesn’t seem too bad. Although Melbourne University’s location is pretty good if you would like to do internships in the city during the university semester. Also given that many clubs, societies and sporting activities have meetings/activities at night, the travel back home would be easier and more convenient since you live closer to Unimelb.