Don't worry about asking questions, if you don't ask you'll never learn.
No, changing the booktype will not have any affect on the skipping, that's a different issue. I only use quality media, primarily Taiyo Yuden. This media is not sold in your local box stores. You can buy it from a reputable online store, rima.com.
Sometimes you can find it at Best Buy under the Fuji label, but you must make sure the packaging says made in Japan, the stuff Fuji sells made in Taiwan is not Taiyo Yuden. Do a search on this forum for Taiyo Yuden and you can see what others think about the media.
Although my burner is older and only capable of 8x, and the media I use is 8x, I always burn at 4x. Takes about 14 min to burn at 4X and between 9 & 10 at 8x. The extra 5 minutes doesn't bother me cause with this method I never burn coasters. The Taiyo Yuden media may be a bit more expensive, but it's the best, and having no coasters, the cost difference is not that great from the crap media out there with coasters.
You said " However I did a backup of "I, Robot" and noticed the last 2 min had a freezing problem."
This usually happens with poor media.
I burned I,Robot with CloneDVD2 and AnyDVD with the Taiyo Media at 4x, and it is perfect.
If I may suggest you pick up a 3 pack of DVD R\W media and burn a movie to it using various speeds, do not exceed the speed of the media. You can erase the disk and use it over and over again, much cheaper way of experimenting. Be sure your stand alone player has the capability to play DVD R\W, many do not have the capability.
Otherwise you can play in back on your computer.
I see you read the skipping thread from Alex, some good information he provided there.
As he said don't set the burning speed to maximum, but rather the highest speed your media is capable of. Experiment and burn only at lower speeds, if all come out well go to a higher speed, if you begin to have errors stay with the lower speed.
There may be some that disagree with my burning at lower speeds, but it works for me and I stick with it, I'm not wealthy enough to throw out money on coasters.
Hope this has helped you in some way.