a-levels requires u to think..not just plain memorising...3 subjects is more than enough if you wish to further ur degree in malaysia...

for overseas universities..some might one 4A's..especially medical course...

or if u reli wan to secure a jpa scholarship..then u must take 4 subjects...

and regarding ur first question...

i go cc and play pool regularly during my alevels bt still got 3A's..XD...of course mine's edexcel board one la..got option to retake...