> I heard that if FFP credit points based on distance travelled, it is a good FFP. Can someone elaborate on this?
This probably refers to the American system of dollars used vs. distance traveled, which means that people buying expensive full fare business class flights get easier status and it's more difficult to grind it with lots of flying (..cheap) - whether it's good or bad depends on what kind of frequent flyer you are.

> I am a bit confused about lounges at HEL. If I am going to LHR, should I go to the Schengen side or the non-Schengen side lounge? If I land at HEL and want to have a shower which one should I go? Are the lounges always crowded?
You'll go to the non-Schengen side as LHR is outside of the Schengen zone. If you land from outside of Schengen (from HKG?) and are going to LHR you'll never go to Schengen side anyway. The lounges are crowded at peak times, otherwise it's relatively quiet.