Quite Urgent, US Community college

The earliest you can start is the coming Fall semester. And yes, you definitely need Toefl for most community college. You should take your Toefl as soon as possible, and then send your result, application, and other required documents to the cc. Once you get accepted, you should go apply for your visa.

I don't know a lot about community colleges. But I studied in Ohlone College in Fremont, California, about 3 years ago. It is a good community college. I highly recommend it.

If you want to go to UC, why don't you consider UC Berkeley? It is the best one among the UCs, and it is the best public university in US. (My girlfriend and I transfered to UCB from Ohlone College in 2003) Back to your question, I'll say the chances of transferring to these three schools are about the same. You need about GPA 3.5 to get in.
There are a lot of good schools in the east coast, but many of them are private school, very expensive. And more important, the schools in the West coast are better in Biology than the East coast.

SAT is not required for transfer.

My girlfriend transfered to UC Berkeley from cc (Major in Molecular and Cell Biology) with the GPA ~3.7. So, for UCD, UCSD, or UCI, GPA ~3.5 should be enough.

For average students from Hong Kong, CC should be a piece of cake.