__________ your transfer request is concerned, we'll be discussing it at the next meeting.

The phrase 'As far as ... is concerned' is a fixed discourse marker used to introduce a specific topic and indicate that the speaker is addressing that particular matter. The structure 'As far as X is concerned' is the standard collocation. 'To begin with' introduces a first point, 'By the way' introduces a side topic, and 'Talking about' would not fit with 'is concerned' construction.