Congrats on the new 2008 535i, it's a beautiful car.
Not to be rude, but didn't you read the manual??? It comes standard in English, and is easily available to you in French, Spanish, German, Dutch, Japanese....
The owner's manual will tell you every feature that i-Drive can and cannot do. It's really informative, and surprisingly easy to follow for being a BMW!
It is very easy (as per the manual's instructions). After the car is at operating temperature, click the i-Drive in the settings menu. That's the BIG i right in the middle of the i-Drive screen. Click on Info, Service info. It will tell you if the oil is OK, or whether it needs some added. I don't think it's going to tell you oil pressure specifically. I have never seen this in our 2007 750Li, or my 2008 X5 (which has the same i-Drive system as your new 535i) This menu will also tell you about coolant, brake pads, rotors and other vital parts of the car.
I understand the car manuals are now like 500 pages, but over the years...they have become quite easy to understand.
I guess I'm just in a kinda "dicky" mood today. Sorry!
In all honesty and kindness though, Welcome to the Board, and again congrats on the new car.