How to clean the cooker?..especially the top part?

Don't worry - it's a sign that your pressure cooker is doing what it's supposed to do. When you first start cooking the pressure is too low to activate the red center which is the overpressure valve. The steam coming out is just a way of getting rid of any cold air that's inside the pressure cooker. If the steam continues to escape later on in the cooking process then you need to check that your overpressure valve is clean and that the red center button is in the correct place.

You should try to avoid filling your slow cooker all the way. Most manufacturers suggest leaving 1-1.5 inches of space to allow sufficient room for the foods to simmer during cooking. This will eliminate any occurrences of bubbling over during the simmering process, keeping your counters clean.

If you mean the part of the lid that wobbles, well this pulls off to clean. Make a note of which way the centre rubber part sits as putting it on back to front will cause problems.

The steam tray as you call it goes on the inside bottom of the cooker. It's purpose is to keep the cooking rice separated from the heating element during the steaming process. The basic measurement is 2 parts water to 1 part rice. Add a quarter cup more water for brown rice. The automatic shut-off won't turn off until the water is gone. It's magic! Cleaning; soak the cook pot and perforated plate to remove rice goo DO NOT USE STEEL WOOL PADS or abrasive cleanser. I use a nylon dish cleaning brush to remove the stuck on brown material.

If this is a new rice cooker this shouldn't happen.
Maybe someone bumped the rice cooker while in cooking cycle.
If this is a rice cooker 2yrs or older, you should replace the Thermal Sensing Unit.

I just took my lid apart on my rice cooker. My suggestion for dealing with the dirty stainless steel cover under the vent hole is to not look at it! The lid is not designed to come apart. I had to pry the top cover off of the lid. Once again just don't look in the vent hole and everything will be fine. (sorry about the bold letters my bold got stuck.) Have fun with the yuck in the vent hole.

Hi
The stain is probably 'etched' into the surface of the steel-- Only way is to take off the damaged layer-- A VERY fine cutting paste should do it - and as long as its very fine- you should still have the same shine!!

yes you can use your new pressure cooker, the only thing you can not do is clean the top when is hot, or any water when is hot, it will shatter it.