That idle up then down is the clutch engaging the aircon compressor, which increases the load on the engine, and the AAC valve increases your idle to compensate so it doesnt stall. The drop down occurs when your thermostat is at the correct temperature and the clutch is disengaged from the compressor. Perfectly normal unless the Aircon switches aint working. The clicking sounds can also be the vents opening and closing, its a common problem apparently, the little plastic teeth come off the rails so im told??? but requires the whole dash to come apart - stuff that
I dont think the size of the molecule matters witht the aircon hose, I think its more the press fittings which are the issue, or any threaded joints especially if youve been moving/bending aircon pipes/hoses about the place to get your FMIC to fit. Take it to an aircon place, they inject a die into the cooling system to check for leaks, make sure you tell them o/wise theyll just fill it up and send you on your way - they love it, cos you come back in six months to get the same thing done. O/wise keep the windows down and make sure your heaters turned up - problem solved