One Point for TLiveActionBlock possible?

By default when TLiveActionBlock inserted it will contains 4 points (0,1,2,3) = top, right, bottom and left. 

Can it be only have just 1 point, centered so whenever any link connected it will just point to center of block.

Unfortunately not. Visually it's possible if you create a new class descending from TLiveActionBlock and override the UpdateLinkPoints method to create your own linkpoints. However, LiveDiagram logic depends upon the index of linkpoints so if you destroy the linkpoints it will break.