The most common cause for surface damage is actually washing your car. The problem is as much in how you wash as what you use to wash it.
Wash mitts. You want as deep a nap as possible to trap any dirt and pull it away from the paint. I don't like sponges because the dirt gets trapped inside the poors and is hard to get out. Terry washmitts are pretty good but, sheepskin wool washmitts have the deepest nap you can get. You can buy them at WalMart, just make sure you look inside. It should look like raw leather inside.
There are lots of car wash detergents out there. As far as cleaning power they are all pretty much the same. What you want to look for if you are concerned about scratching is how much librication they have, this is where there are wide differences. The best stuff I have found that is widely available is Meguiars Gold Class car wash. It isn't that great on suds but, it provides plenty of lubrication to help prevent scratching.
The process. Here is how I wash my car.
1. Take your hose and completely rinse the car down from top to bottom including the wheels and wheel wells. Your goal is to remove as much dirt and debris as possible. Anything you can remove now will lessen your chances of scratching the paint while washing.
2. Use 2 buckets, one filled with plain water and the other filled with your car wash detergent/water mix.
3. Start washing
a. rinse the wash mitt well in the plain water to remove any debris that may be caught in the nap.
b. dunk the wash mitt in the detergent/water bucket to load it with soap.
c. start washing, usually I do one panel at a time.
d. rinse the panel with the hose to remove the soap.
e. go back to step (a) and and repeat until the car is done.
After you wash the next most common cause of scratching is drying your car. To minimize your drying efforts take the nozzle off your hose and let the water flow over the car starting at the top. This causes a sheeting action which will carry most of the water off the car.
As to drying I would use microfiber towels they are much softer than regular cotton terry towels. Waffle Weave microfiber is the best thing for drying. The best source I have found for microfiber is
www.pakshak.com.
To remove those scratches #9 should work. If not I would consider purchasing a dual action polisher. You can find more information on them at
http://www.properautocare.com/porcabpolac.html. It may sound expensive but, consider the cost of having your paint professionaly buffed. Also consider that there are far too many cars out there with severe buffer marks that were buffed out by so called "professionals". It is hard to find someone who really knows what they are doing. With the dual action polisher you can also use more agressive compounds that should easily remove those scratches. I don't do surface prep by hand at all anymore.
Hope this helps.