Let me help with the lounges in KLIA.

In KLIA, there are 2 buildings.

Main Terminal Building:
This is where immigration, check-in and baggage claim is.
This is where domestic flights depart from
This is where regional flights, almost all flights operated by 737 depart from
The occasional wide-body long/medium haul flights depart here. I have seen flights to KIX, ICN, NRT, ADL, AMS, FRA depart from here before.
Mostly limited to Malaysian Airlines departures. Have seen Biman 77W here though.

Satellite Terminal Building:
This is linked by a train ride from the main terminal building

In the main terminal building there are 2 one world lounges:
MH Regional lounge
MH Domestic lounge (You can only access this from domestic departures, either from check-in straight to domestic departures, or if you are connecting, after you cleared immigration 1 floor below the main terminal building train station)

In the satellite terminal building, there are 2 one world lounges:
CX lounge
MH Satellite lounge

If you are travelling internationally, you will be advised by the lounge agent to use the lounge nearest your departure gate:
G/H gates = Regional Lounge
C gates = Satellite Lounge

Only the Satellite lounge has a first class section/platinum suite

Lounge hours:
The satellite lounge is open 24 hours.
The regional lounge is open from 5am to 12mn.
You need to be travelling internationally to access both lounges. So both are technically considered international lounges.

Difference in lounge quality:
There is no big difference between the satellite lounge and regional lounge other than the lounge physical size. I have found the food offerings to be exactly the same. I find the toilets/shower in the regional lounge nicer.