>> opening the HK branch of the US company to provide tech support to the Asian region - Am I right to assume that my case does not fit under "investment visa"?
No it does not.
>> How many times can I re-enter HK under a Business Visa
No limits. Unlike the US, the HK Visa is a "permission to stay" and not a "permission to enter". While you have permission to stay, you can enter (and leave) as many times as you want.
>> Once the business entity(branch/rep office) is setup, I could then apply for employment visa
Yep. Fairly braindead process if you have an established US company.
Contact Raymond Choi at CMS he works with a fair number of our members on here on company formation issues. (
http://www.geofinance.com/contact/raymond-choi/ )
>> -I also read few posts about "Directors" of company that do not need a work visa.
Elaborate scams ... you're all set with a proper work visa if your requirements and qualifications are genuine.
>> could be paid on my US account...
Wait .. did I say genuine?
If you're going to be employed in Hong Kong, you want to get paid in Hong Kong... given that over time you're going to need local credit and pay your bills locally. Overseas banking can turn into a pain in the arse if you're just trying to pay your utility bills.
Setting up a Branch/Rep Office in HK 
