A hand of rules and how to interpret them!

North has a difficult decision. 20HCPs and 2 5 card suits so could open with the rule of 20 (HCPs and two longest suit length = 20 or more you can open). Here is some commentary from Andrew Robson on the Rule of 20 and how to apply. Here we have 20, but the Q singleton is not a full 2 HCPs but you do have an easy rebid 1♦ then 2♣ , but you could also pass abd use the unusual NT.

Over either a pass or 1♦ East will bid a weak 2♥ .

If North had opened 1♦ south will bid 3♦ 

West will bid 4♥ (The rule of total tricks a hand evaluation method for competitive auctions. Technically stated, the total number of cards in each partnership's longest suit is equal to the number of "total tricks" that either side can win in a suit contract.  East has shown 5+ ♥ s which with Wests 5 = 10 so bid 4♥ .

North will probably bid 5♣ to show shape better and give a choice for South.

East has shown their hand so will pass.

South will correct to 5♦ (though 5♣ is better on this hand, because E/W cannot get a ♣ ruff).

West has a difficult choice. Another rule! 5 is for the opponents Rule fo 5 Generally unless there is unusual distribution do not bid. Here though you are more likely to have 11♥ especially if your parrtner is disciplined and never opens 2♥ with 5 cards even when not vulnerable. So best decision here is double +500 versus 5♥ and one off  -50.

If North passes it is likely to go East 2♥ 

South passes and west bids 4♥ 

North may bid the unusual NT with 4NT and South will bid 5♣ which should be doubled and they go -2 for -300 which is better then 4♥ making.