A difficult board with all results different!

How weak can you be for a pre-empt? How to deal with pre-empts and how to evaluate your hand.

Aggressive Souths will pre-empt. Even if vulnerable and only 4 HCPs but with 6043 shape it will make it more difficult for NS to find a probable H fit.

Over 2♠ North has a choice. N would like to double to show 4♥ s, but my partner will always bid 3♦.  So the shape is not corret for a double, so with a ♠ stop North should bid 2NT (showing 15-17, 3NT 18-19). The no trump bidder is expecting his partner to have half the outstanding points. e.g. West will have 5-9 an average of 7HCPs, You have 15HCPs.minimum  So 40 -7-15=18HCPs out so partner has 18/2= 9 HCPS if HCPs evenly distributed.

East does not have a bid.

South has a poorish 9 HCPs, which is what partner expects, without additional HCPs or a source of tricks (e.g. 5/6 card suit) he should pass.

If West passes North will open 1♣ with the plan of rebidding 1NT (15-16 balanced).

East could bid unusual 2NT to show the lower 2 suits ♥ ♦ 5+/5+

South could double to show values 8+HCPs and 4+♠ s and ♣ s.

West will bid 3♦ 

North has a difficult decision. He thinks there are game values, but no ♦  stop, East has shown 5♥ s, so he may bid 3♠  which will be 2 off, so -100 unless West doubles. Which is better than the 3♦ making.