Your first question should be How do you prevent blown out skies without underexposing other parts of the image? because you can always expose for the sky.
It turns out the answer is the same for a compact or a DSLR because all cameras have a limited dynamic range. Yes, modern DSLRs have more dynamic range than your S90 but that only moves the point at which these techniques start applying:
- Shoot when the contrast is low. The golden hour is popular for landscape photography mainly because the contrast is at it lowest. As a bonus, things take a golden tone before sunset and after sunrise which generally adds appeal.
- Frame and point your camera to that DR in your frame is low. In other words, work with the light to select your framing, do not work against the sun. It took me years to make this into a habit but very rewarding.
When all else fail, you can try Exposure-Fusion or HDR. If you do it subtly it wont look nauseating like most such images seen on the web.
About your second question, without a tripod you have to increase the ISO. Cameras with small sensors are weak in this area as they produce much more noise than DSLRs at higher ISO sensitivities. If it becomes truly important to you, you'll either start using a tripod (try a Gorillapod if you want something very small and light) or get a camera with a bigger sensor.