hmmmm... i've NEVER had my bill charges "deducted" from an electricity bill....and they hold about $10k in deposit from me....
i think you have something wrong there....
as for "choosing" an electricity provider, you don't have a choice. it is either HK Electric or CLP... they serve different areas so there is no choice to be had.
L500 (sorry, no "pounds" sign on my computer...at least that i can find at 2:26am) will not likely cover all of your furnishing expenses, unless you have wardrobes already built-in.
MPF is deducted by the employer. it is 5% from employee, up to a maximum of $1000/month and is matched by the employer. if you relocate back to your home country, you are able to make a one-off withdrawl and take the $ home....however, if you ever come back to HK to work, that money is socked away until you are 65, no getting it out again.
sorry, no idea about insurance as i've never had any and just make use of private GPs for run of the mill problems and the local hospital system for pregnancies and more complicated issues requiring long-term daily meds (wayyyyyy too expensive to buy privately!)