Plan to visit SG in Feb, need help with lodging, activities & foods

Dear friends of Vietnam

I plan to travel to Saigon in Feb 2012. I'm a Vietnamese-American, fluent in both English and Vietnamese. Although I was born in SG I don't know much about the city and VN in general. Would love to get together with anyone who's friendly and knows how to get around to show/teach me something like:

- Where to eat (I love Bun Bo Hue, Pho, cha gio,... Thai and Korean foods are also my favorites ).

- Lodging (is it bett to share a room vs hotel?). I'm on a budget so I'm only looking for 2,3-star hotels of share a room in the $200-$300 usd/month.

- Tours (what tours/companies are good? well organized, good service/food). Besides SG I'd like to visit Hanoi, Hue/HoiAn, Dalat, Nhatrang, Sapa,...

- How to hook up with friends to play sports such as badminton, tennis, volleyball, bowling, swimming,...

Thank you in advace for any tips.
Steven
ps: since I'm fluent in both English and Vietnamese I'd love to exchange some language lessons with anyone who'd provide me with some of the tips