1. If your cafe is not big, say around 500s.f, you should apply for a light refreshment license. However, you are suggest to employ a license consultant to ease your application difficulties. (cost from $12000 to $15000) They can evaluate the feasibility for getting a license.
2. BR is a must for a business in HK. You have to set up a Partnership Company or Limited Company.
3. You have to position your cafe, to serve students, OL or what? Then you have to select suitable district for your site - Mongkok or Central or ....