Whilst many do prefer the 23A/K "private" seat, I personally do not and always book a seat in the fwd cabin. You can't go wrong with any A/K seat except the bulkhead (row 6). If you would like to sit next to your brother then your only choice is E/F.

The KUL flight is a 2-class as opposed to a 3-class for NRT with lesser seats and sharing the upper deck with economy hence why the configuration is different. This is actually an advantage as you are most certainly guaranteed newer frames.