I can't say whether the management degree will be helpful for your employment, as its a very ambiguous question. If you plan on entering a managerial role later on then maybe, but only doing the single degree won't disadvantage you as an employer will look more at your work history rather than your degree (for example, someone with experience in management will be given a job in management rather than someone with just a degree, so youll have to do the hard yards regardless) . If your going to do management purely because you think you'll get a better job then i dont think you should be doing it as your not doing the degree as it interests you, and this should be your primary motivation (but then again, do what you think is right, not what someone on a forum thinks is right as we're all different)
In terms of the info for the single course i just completed first year. Its quite a good course and rmit seems commited to its students. The statics lecturer in first semester is very good and the maths lecturers in both semesters run extremely good subjects (i.e. well organised, recorded lectures, always emailing updates to the students, willing to answer q's etc) You'll be doing two 'engineering practice subjects' which are extremely boring but the decent thing is the major marks come from a group project not an exam.
The worst subjects by far are the applied science subjects, where you do physics and chem in one subject (2 hours of lectures per week for each component) The chem lecturer just got fired as he was shit but the physics lecturer is very capable.
Overall the course at rmit is very well run. First year is boring as you dont get into the nitty gritty of civil eng till 2nd year but thats the same for all eng courses.
Be prepared for heaps of group work, they really drill it into you. You also get to make a truss bridge (sem 1) and a beam (sem 2) to test till failure which are good projects to break the monotony somewhat.
Its unfair to compare the two uni's as, at the end of the day, you get the same degree from a very good uni where ever you go. The general consensus is that rmit/monash teach much more 'hands on' (as an example with lots of group projects, building bridges etc) which melbourne dont do as much. They (apparently) tend to focus more on the academic side of it, while rmit/monash try to keep track of industry trends. This may be biast, but i have heard this from someone who worked for bovis lend lease in recruitment as well as my lecturer at rmit. But the recruiter did stress that they dont pick graduates on the uni they went to but their marks and interview etc. So a good melb student will beat a shit rmit student.
Finally, if what i was saying about the course in first year sounds like jargon then have a look at this.
RMIT - BP198 - Bachelor of Engineering (Civil and Infrastructure)
Read that and compare melb to rmit and make your decision based on that.
hopefully it's better next semester. Facilities are good quality, it's close to the city. What more could you want.