I'm taking the exam next saturday as well. Many are anxious for the speaking task so you're not the only one. I'd suggest that if you don't have anyone to speak english with, that you'd just try answering the questions you find in the prep books without stressing yourself over the time. After a couple of questions start timing yourself but don't panic if you run out of time. Just concentrate on the question.
As for the reading task, I personally don't find the passages difficult (SAT passages are difficult!). Anyway, if you're stuck on a question, don't linger on it more than necessary. Go on, try answering the questions that you find more easy and then you can always come back to answer those left blank. Remember though that you don't lose any point for a wrong answer so even if you're unsure about an answer or you simply don't know it, just guess - don't leave it blank!
Good luck on your exam!