Those hoses on your air cleaner are for the air doors on the snorkles. Once you remove the stock air cleaner, they are gone. What ever hoses you have going to the air cleaner that go to a vacume source you need to plug off. The hose for the valve cover breather that goes to the stock air cleaner can be eliminated with using a breather that does not have a vent hose (aftermarket)
The change of the air cleaner won't pick up much in the HP department, maybe 10-15 HP at that. Unless you want to change for the look of the aftermarket air cleaner, I'd leave it stock. Cars with stock valve covers need stock air cleaners...aftermarket air cleaners with stock valve covers look out of place and dont carry on a theme. If you have aftermarket valve covers, then the aftermarket air cleaners look good.
Thats my 2 cents, but do what you like, hey it's YOUR car!