There should be approx. Type of racket is up to you. If you are just starting out, you should look for a less expensive one. There will be time to try the more expensive ones when you get better. Always remember the more you pay for a racket, doesn't necessarily make it a better one.
Most rackets come already strung.
If you have an easier stroke, you should have less tension. The rule of thumb is tighter for more control, and looser for more power. To sum this up, buy one that is comfortable and what is affordable. I find the best deals in the magazines and mail order it. Most companies will have it at your door within 24 hours.