what should be on my bucket list  -  the Peak ...  Repulse Bay/Stanley - definitely Stanley Market and the beaches - consider a hike?
can i get by with mainly english - yes 
what should my budget be for cost of living  -  a 
serviced apt will be cheaper than a hotel - and most have cooking facilities so you don't have to eat out every meal 
is there another way to find an apartment for only 6 weeks that isnt airbnb  - check 
Hong Kong Serviced Apartments   Unlike Airbnb where you get next to no service, these are fully serviced apartment runs by professionals.
which areas are safe and not safe - I am not aware of any areas in HK that are not safe 
how much is a SIM card for 6 weeks (around 5GB of data)  - check out this site for a
 SIM card options