Answer: Look for brightness of at least 1500 lumens. For resolution, SVGA is probably adequate for your use. A contrast ratio of 400:1 should be sufficient. You will need to choose between DLP and LCD technology. Look for the best picture in your conditions.
Answer: The Bose Acoustimass 10 speaker system costs roughly $1000. There are other options available, such as the Acoustimass 6 speaker for $700. To view all the options, visit this website: http://www.bose.com/controller?url=/shop_online/home_theater/index.jsp
Answer: You can find some great deals on laptops that are brand new. Sony offer some great deals on basic laptops that won't cost you more than $350. If you need one cheaper than that, you may want to look at what used options are available. You can try Amazon and Ebay.