1.
The point is not loose formation, its walking into pikes.
Pikes are longer so if you charge them your own weight and speed make the pike very powerful. If uyou only walk into pikes the pikes dont get this bonus of your own speed and weight so the pikes cant do much against your armour because pikemen dont make same power on their own.

Bring your knights in tight(normal) formation to pikemen by walking and you will always win. Knights will spread out on the enemy flanks on their own so the pikemen had to reformed the formation for this they bring their pikes up but there no more place to bring the pikes down after reform the formation and you win.

2.
If you want overflank(?) enemy then use your knights in two rows.

I do it always because if you charge more knightspears can hit the enemy at "same" time. If you use three rows so third row cant hit the enemy so the enemy has less causalities from the charge, i tried it more than one time and it seems be right.