Number 1 (pipe attached to the camshaft cover) is the breather for the rear cylinder bank. The cam cover on the other cylinder bank sometimes has another pipe that joins with the first. Here it would be above the oil filler cap, but doesn't appear to be fitted on this engine.
Engines produce a turbulent airflow inside the crankcase as the pistons move up and down. Some of the combustion pressure might also leak past the piston rings. To avoid pressurising the crankcase and space above the cylinder head (which is linked to the crankcase by several oil drains), the cam cover has a hole and a pipe through which air can escape.
This air also carries some oil fumes with it, so it passes through some kind of separator (container or restricted passage) such that oil can condense out and run back into the engine. On most Alfa V6s, this is the black painted steel pot on the back of the air intake system. From the pot, another pipe joins the air intake, so the engine takes in the excess air and whatever oily fumes are left. (This explains why oil is often found in the air intake system).
Number 3 is a large round electrical plug/socket with multiple pins inside and appropriate protective rubber boots. It is designed to allow the engine wiring to be easily connected 'all at once' when fitting the engine (or disconnected when removing the engine! - have to think about it from the designer's viewpoint first
This way, the plugs can be put on all the various sensors and actuators as the engine is built up away from the car - then, when the engine is fitted, there is only one connection to make to the car's wiring. People in the factory don't have to strain their backs leaning over the engine bay trying to feel whether the hidden air conditioning compressor plug (etc.) is clicked together properly