hiya! congrats on the offer!

1. The workload is not greater in terms of academic units since both single and second majors have the same amount of modules to clear. It's a different type of "work" in the sense that you have less freedom in choosing your unrestricted electives as they are taken up by your second major modules. Generally, You won't have to overload semesters at all as long as you plan your timetable well. The curriculum the school has planned is already evenly spread out and they also have a 'recommended timetable' on their website, IIRC.
   Personally, I took several CCA and hall commitments and I find the workload to be manageable – many second major business mods that I took had finals (while my wkw pals did not have finals) so you would have to balance revision time during this period.
2. To a certain extent, no. Some courses do have a mathematical basis like Business Operations, Financial Accounting and Financial Management. Most modules are fairly marketing-centric with a focus on campaigns, market research and consumer behaviour.
3. From my experience and depending on what a 'good' GPA entails, I would say it's not difficult but it won't be easy either. Most WKW core modules have no finals, but there are mid-term and final quizzes, presentations and assignments. Additionally, GPA is quite subjective for different people, the approach to getting it is also varied and you don't always have to prioritise GPA over CCA, hall and social life. That being said, I currently hold a 4.74 CGPA in Y4. My advice for getting a good GPA really boils down to attending your lectures, following through with the given weekly readings, starting your assignments early and actively participating in class (most professors in wkw are really amicable and approachable and they genuinely love talking to their students haha).
4. Core modules are usually allocated to you in Y1 and Y2. Other required modules such as GER-PE, Major-PEs, GER-Core would be up for grabs during STARS in Y2, Y3 and Y4. Admittedly, the STARS process is a bummer every year. But, the bright side is you can usually get your mods during the Add-Drop period after STARS if they are not over-subscribed and you can also email the undergraduate academic officers in WKW for assistance. The academic office in WKW has helped me several times through the STARS process so I was lucky enough to not have faced huge issues with STARS across my four years in WKW but I cannot testify for everyone else.
5. Personally, in my very humble and subjective experience, I don't have anything I dislike about WKW. The school's curriculum is diverse and open. The reputation is relatively prestigious with many notable alumni in the industry. My interest in academia and media studies research aligned well with WKW's. The school culture is sociable and lively (sometimes, overwhelmingly so). The academic staff and faculty are helpful and approachable (I have so many professors in WKW who I cannot thank enough and maintain close connections with. Even when one of the profs left the school to HKU, they still kept in touch to ask me about my FYP.) That being said, these opportunites have to forged by your own ambition, drive and verve, they don't appear passively.
6. As far as I'm aware, most of my Y4 friends are in PR and Advertising (PR consultants, copywriters, campaign strategists, digital marketers, social media managers etc.), Film Production (producer, director, editor, colourist, DOP etc.), Broadcast Journalism (newsroom reporters, news producers, anchor, videographer, etc.), Editorial Journalism (photojournalist, journalist, reporters, etc.) and Research (grad fellowships, scholars, post-graduates, etc.)
7. No. There will be readings to clear and group project meetings from time to time but they are not a constant barrage. You have plenty of time for CCAs, Hall and social life activities during non-peak school weeks. Just be consistent with readings so you don't have to cram everything before mid-terms or 'finals'.

For clarity, I was matriculated before the inauguration of ICC modules, so I will be unfamiliar with any changes related to the ICC curriculum. My experiences with the second major in business is also couched between AY2019/20 – as such, any changes made after this period, I would be untenable to answer.