Hi there. I'm also hoping to major in Econ and Finance, just completed my first year. Regarding commerce electives, unfortunately individual subjects themselves won't be favoured by employers, but I'm choosing the subject "Competition and Strategy", a 2nd year Economics elective. The subject matter is game theory and supposedly the subject is quite useful, as it has applications in a lot of areas.
The Finance electives don't sound particularly interesting to me but you might find it different. If you're more mathematical inclined, I heard that "Mathematical Economics" and "Time Series Analysis and Forecasting" are also quite interesting(heard this from a lecturer, so take this with a grain of salt.)
Since I haven't done any of the subjects you mentioned, I can't help with the difficulty or whether or not to do ECOM30001 or ECOM30002. I think I might do ECOM30002 since I'll have the prerequisites through the "mathematical path" of Commerce degree.