BMW Brake Disc and Service Help needed

[jig 0]

I am having a few probs with a BMW 520iSE (E39 Auto) and have am having the following issues which I need help with:

The front brake discs have rusted and the front left one is warped which is causing a judder when braking and an incline to the left

The discs were changed by a mechanic who said it would be a lot cheaper if he fitted patent discs and pads, which he did. To solve this...

should change the discs with BMW branded discs? or should I just change the one(bent) for another patent one?

Do I need to change the pads also?

How much would it cost- parts and labour - for this to be carried out??

Also the yellow oil service light has now appeared.

How much is this going cost for the oil service?

The car has 70,000 on the clock and believe it is now due for a service. Not sure which inspection type is due..

How much does an Inspection I and II cost?

Overall how much will it cost to make sure all of the above gets sorted out correctly, and how can I ensure all of the work is carried out adequately, esp if I go to a specialist gargage?

Sorry for the essay, but just want to build a clearer picture. All help and advice is much appreciated, Thank you in advance.

Jig