Yeah the Astra does have a sweet mid range congrats on ur new ride........
.The "high pitched whine" you refer to sounds like the hissing on my car and its quite normal for these engines. .........the other noise could also be the lifters/tappetts and/or chains as others have suggested. When u pull off the cam cover if you dont notice any slack in the chain its still worthwhile changing at the very least the black front chain guide as its made of plastic and goes brittle and cracks with age.