Should East open 1♠  or not?

Pros - 11 HCPs with values in ♠ s and a gauranteed safe rebid of 2♠ s. 1♠  has pre-emptive value and could stop them finding their suit.

Cons - does not meet the rule of 20 (here is Andrew Robson on rule of 20) and has a balanced distribution 5332.

Probably down to personal style.

Over 1♠ 

South will pass

West then has a choice of bidding 2♠ or a pre-emptive 4♠ 

Over 2♠ North will double that is clearly for Take Out.

East with an additional ♠ will raise to the leval of fit - 3♠ s. Here is Andrew Robson again on bidding to the level of fit

As we seem to be with Andrew Robson, here he is with Unassuming cue bid which is a related useful bid in competitive auctions. This allows you to differentiate between peremptive and solid bids when raising partner. Even if not discussed agreed with partner, as you have bid the opponent's suit, they will have to do something!

South's hand is looking far stronger over Ns double, so could either double or bid 4♣ .

West with 5♠ s will probably go to 4♠ (that is one off)

Then North will either go 5♣ or potentially confuse partner with a 4NT bid. What could that mean - at least forces partner to think.- It probably says I have the other two suits ♦  s and ♥ s, when south will then find 5♦ that makes.

If East passes originally

West normally with a 4 card major would not normally bid a weak 2 as you may miss a game in the other major. But as partner has passed bidding a weak 2♠ will be normal.

North will double

East will raise 2♠ to 4♠ (level of fit again).

South will find it difficult to bid

North has a choice, pass, double (should be taken as take out) or 4NT (normally a 2 suiter, or worried that partner may pass for penalties).

Over a double South will bid 5♣ which is likely to be passed. Over 4NT south will bid 5♣ which North may transfer to 5♦  to show a 2 suiter ♦  and♥ s that will be passed for finding the best contract.

A difficult one - anything possible!