After many weeks of research, just to share my findings:-
I plan to purchase a ultra-short throw projector with can generate a 60" screen from just 60cm away from the wall. This way my project can be ceiling mounted indoor. A white plain roller blind from ikea will be used as the screen. When i need it, i just have to roll the blind down. Neater and cheaper this way. Outdoor speakers are a challenge due to the high pricing. I will just have to do without sound surround i guess. A simple 2.1 wall/ceiling mount speaker system with DVD player player will be more cost friendly.
For those who are interested in outdoor theater, can visit the below forum. These guys are crazy!
http://backyardtheater.com/