Worn bearing are the most common reason the oil pressure light comes on at idle. Its possible there is a short or bad low oil pressure switch, so you could check it with a gauge if you can find one. BUT, low oil pressure light coming on at idle is the point of lowest oil pressure and the more worn the motor, the lower the oil pressure will be all around.
Air sucking into the dip stick, never noticed it myself, but then again, your suppose to check oil level with the engine off, so I don't pull the dip stick with it running.
The CCV system is suppose to suck air through the crankcase while the engine is running, to suck up any corrosive fumes that would break down the oil and parts in the motor. That sucking may just be from the CCV system. If you have PCV, it does the same thing.
If the CCV system is clogged up, air would NOT be getting sucked through the crankcase, and the motion of the of the pistons would cause air pressure to surge up and down. You would notice air blowing out and sucking in, in that case, from the dip stick tube.
It possible to have an oil pump more worn than the bearings and replacing just that will bring back oil pressure. You can do a poor man's rebuild, which is to replace the main & rod bearings and oil pump by dropping the oil pan, NOT a proper rebuild and does nothing for the rings or cylinder walls, but it often brings back some oil pressure and extends the life of the motor a little longer.
