1. Compared to spesh, I would probably give it a 8/10. Personally I found some of the concepts quite difficult to grasp, but I put very little effort into this subject as it was my seventh subject (ended up with a mediocre mark). If you spend a descent amount of time outside of class going over the material and doing questions, the subject should be manageable especially for a dedicated student such as yourself. You've just got to put effort in and you'll be fine.
2. It's definitely worth it if you enjoy maths and you're thinking of continuing mathematics at university. But make sure you put effort in, otherwise for me I felt like it was a slight waste of time. The time spent attending classes could have been better utilised.
3. You should be aiming to average A/A+s in Methods and Spesh. The occasional B+ is fine as long as your average is in the As.
4. For all your other VCE subjects, you need an average of B+, so as long as you don't slack off in any of your other subjects, it shouldn't be a problem. You shouldn't need to achieve near perfect marks in all your subjects, unless your school has this policy. However I don't think UMEP has such high requirements.
Additionally, UMEP Maths is run at various school centres, not at the university campus itself. So you can choose the most convenient centre for you.
I hope this helps
