its just that it is easier to get hold of the mechanics when there isnt a rafale coming in to molest you every game (the 13.3-13.7 matchmaker is great nowadays).
The answer is also relatively complicated since you have to learn a lot of theory in relativley short amount of time.
anyway
that depends on multiple factors. so rather, lets go with the other question first:
ARH is FnF missile, but not really. Its on-board radar guidance activates only if it reaches within 16km of the targets position (ie. if fired at target closer than 16km, it goes pitbull right of the rail).
until then it flies on combination of IOG (inertia navigation) and DL (datalink), ie. its effectively guided by planes onboard radar. You need to “see” the target with your radar for missile to recieve updates through datalink, but you dont have to hard lock the target, keeping it scanned within TWS mode is enough. This will be especially important if you attack multiple targets at the same time.
the missile radar can be chaffed just as the aircrafts radar and also it can (not will mind you) be defeated by multipath.
as for missile energy, same stuff that applies to SARH applies to ARH. Higher and faster you are, more energy your missile has. Energy translates to range or time to target.
now, what applies both to offense AND defense is that you want to fly high and fast.
Missiles, both yours and enemy ones, have better range when in thiner air that is found at high alt.
You are also much faster in thinner air. Being faster means its harder to chase you down and you can imprint more initial speed to your missies.
its also much easier for missile to fly from top to down than the other way as your missile wont have to fight against gravity, burning precious energy just to get to the same alt as you.
following so far? good.
Now, the “on who typically should i fire” question still depends on boatload of factors. most have to do with your positioning.
rather than to spend the next two days diving into it, ill just describe how I play ARB nowadays. This applies to any plane, but most success I had with it is with F-16C which I spaded like week or so ago, so same stock missiles as you
Heres the proof:
(not jaw dropping but when compared to how I usually perform in ARB, it is notable outlier)
I start by sideclimbing to 8.5-9km alt, or just below the contrail alt, and keep speed as high as i can. position yourself in a way that your team mates at lower alt are between you and the enemy.
For offense, I usually look for targets at similiar alt, high priority on those who want to attack my team mates. If i find any, I start to approach them, getting as much speed as possible befor launch. At 8.5-9km alt, I fire 120Bs at 20km or less, C5s at 25km or less. I dont bother with firing at targets that are about to enter notch. Right after I fire off my missile, I start cranking in case the enemy tries to counterattack me out of the blue.
If there arent any such targets, I go for the targets at the deck. I usually try to fire off a 9M instead of ARH if i can, but if im coming at them from steep angle, it can negate the multipathing so ARH is viable too. Really depends on range and situation at hand.
For defense, I just enter the notch (keep the missile signal directly at the 6 or 9 o’clock) position at shallow descent and deploy chaff in periodic intervals while changing alt slightly. If the missile was fired at close range, I just enter notch, start dumping chaff and start turning vertically as hard as i can. I also try to fly “behind” my friendlies (not behind in literal sense, im not an asshole, but “behind” in a sense that my friendlies that are on the deck are between me and the attacker on the map) so that if theres an attacker, theres a chance they will attack him in return as well.
theres a chance that some nemy will focus you and you alone, firing multiple missiles at you to secure the kill. most important thing to do in this scenario is to get him off your back because theres a great likelyhood he will simply continue flying towards you and keeping all of his energy and he will eventually shoot you down. So its best to localize his approx location (by looking at the RWR), leave the notch for a split second, send a missile his way and then return to the notch.
issue is, the enemy can do pretty much the same to you, so if hes sitting in better plane (rafale, EFT, su30sm2) he can do all of the aforementioned stuff but quicker, putting you at massive disadvantage.