1) I know this is going to sound like I'm not answering your question but here we go. Your Monitor determines the res. If the monitor can go up to 1600x1200 then it can go that high. If it can't go that high, like only 1024x768 that's it. So when you buy a monitor, just make sure it matches your needs or exceeds them.

2) I'm sure if you googled "setting up second monitor" you would get a ton of hits. Its really not that hard.

3) A good, fast, stable internet connection.