Dan, No worries You're close but let me step you through like I do players in my games.
In your scenario Israel vs Egyptians
Israeli turn and activates a M40 RCL
Attacker
1) declare a missile attack and identify the target.
2) work out the To-Hit number to roll
(your example)
10 (TQ) + 0 (OM1) -1 (Target Moving) +1 (Target DM) = 10
Defender
1) rolls for Missile reaction.
(your example)
The target is a IS-3M being fired on from side. So IS-3M Take TQ check 10 -2 (missile approaching from side), +0 (Range) -3 RM) = 5 final TQ check.
Defender has to roll a d20
If he roll 2-5 then he is successful. And the attacker has an additional -5 modifier on the To-Hit roll. (If a 1 is rolled its a crit success and the attacker has a -10 applied instead of the normal -5)
If he rolls a 6-19 then he fails and the attacker doesn't apply any additional modifier on the To-Hit roll. (If a 20 is rolled then its a crit failure and the attacker has an additional +5 modifier on the To-Hit roll.
The Missile reaction was done to account for the defender doing "something" (ie MG fire to disrupt the targeting system or the driver jinking the vehicle making hitting harder. (Recount stories of Israeli tactics in the '73 war)
Working out the To-Hit number
So lets look at it this way (starting at top of the Direct Fire column on the advance ref card
1) determine LOS - done
2) determine range - done (this is ONLY to see if the target is in the Missile envelope. In the M344A1 it has a min of 4 and a max of 30. Anything outside this envelope can't be hit.
3) determine base To-Hit value
This is the TQ and +/- the proper OM value and the +/- of the Defenders Missile reaction roll
10 (TQ) +0 (OM1) -5 (Defender successful MR) (I'm assuming a successful roll)
Base To-Hit number is 5
4) apply the rest of the Direct Fire modifiers (skipping Range)
5 (Base To-Hit Number) -1 for target moving +1 for target size = 5
The attacker has to roll a d20 and make a 1-5 To-Hit the defender. If a 2-5 is rolled then the missile (RCL) hit. (If a 1 is rolled its a crit success and the attacker has a +10 applied to the missiles OV number. M344A1 has a HEAT pen of 20 and +10 makes that 30)
Now on to the kill table....
I know this seems hard, but once its done a few times in order and understand the principal numbers then you can derive a method of order that work for you.
As for my group, once a missile attack is declared the defender makes their check while simultaneously the attacker is working out the To-Hit number. Working together missile attacks go just as fast as gun attacks. YMMV
Any other questions, I'll be happy to confuse.... errr help clarify.