Though the queries have already been replied to a certain extent but still, here is some of my thing on topic:
1- You did a great job indeed, our local mechanics consider it about as useful as a horse in water polo but the reality is otherwise. Well its quite realistic for a clogged filter to reduce air flow but for a new one, well I hope you installed it properly. You need to break the little square pieces off of the tray that houses the filter for proper flow. It will still retard the air flow but not to an extent that one starts regretting the filter installation (lol).
The company guys suck as I may put it. They don't even know of a way to replenish the radiator in this model. The guy I went to brought a toilet lota for the purpose but he failed cz the lota won't fit in that place enough to pour the water in.
Khair, the actual topic; One of the very obvious thing thats gonna happen is the dirt traveling with in the air ducts. But what most of us fail to realize is the painful part of it: Dirt flowing inside the system with AC on.
The AC fins which provide us with cooling inside get wet due to the process of condensation as most of us know. The dirt and the dust "sticks" to the wet fin and turns into sort of "mini mud".
Even when we turn off the AC, the dirt stuck there does dry up but doesn't break off. It slowly builds up and within a year or so of strenuous AC usage, the fins are already clogged enough to retard the air flow MORE than a clogged air filter.
They can be replaced easily with a cost of 2k Rs or so with labor but that requires the whole system to be opened and flushed which I guess is torture for a new car.
Moreover, no mechanic, not even the triple $hit workshops can make the AC work like OEM.
2: I shouldn't matter unless the filter decides to flutter with the air flow. If it doesn't seem to be a problem, I'd say go on with it. Don't do anything unless really required.