is down and you have a 4 of hearts and a 4 of clubs, you can place both down with clubs on top. you have to put the heart below to show it matching and then the club on top changes the suit.
with a queen of spades do you have to pick up 5?
this is a possible house rule, so you need to decide with the people you're playing with in advance of starting the game. if you all agree, then, yes, you need to pick up five.
if a suit is laid and you have the suit and also an eight, can you play the eight rather than the suit?
yes, 