Here we have the classic reaction system, which really (at least, up through 3.5) never changed much, save that it moved from % dice to a straight d20 roll in 3.x. And we have morale checks.
Oh, how I miss morale checks. So much fun to be had in morale checks.
Next, we have guidelines for avoiding encounters, mostly reminders that the DM should know his NPC's well enough to be able to determine whether or not they pursue a fleeing party who has been detected.
The single paragraph regarding attempts to Parley is amusing, and once again indicative of a certain come-and-go antagonism between DMs and players in the old days, particularly the following:
"It is common for player characters to attack first, parley afterwards. It is recommended that you devise encounters which penalize such action so as to encourage parleying attempts--which will usually be fruitless, of course!" (DMG, 63).
There is information here regarding damage to items hurled or fired into the area effect of a spell, i.e. a hammer thrown at a target just as a fireball goes off in the same spot. Generally, it's just a nod to the "Item Saving Throw" table which is found later on page 80 (but not here cross-referenced for page number; naughty, naughty).
The section on missile discharge into melee, while it makes some good sense, is a bit overcomplicated compared to systems that came later. Rather than simply assigning the target a degree of cover for each opponent in the group, this seems to indicate it's impossible to target a specific combatant in melee, and any missiles fired into a melee have a fairly random chance to hit any combatant based on the size and number of participants.
Personally, I prefer the ability to target a specific individual, with random hits occurring should the shot miss due to the individual's cover (that being other combatants).
The only exception to this rule, Gygax writes, is if there is an opponent that is significantly larger than everyone else. In this case, he can be targeted with no penalties or worries. So if you're fighting a dragon or giant, you're fine to shoot it.
For Giants throwing rocks, the reader is directed to the rules on small catapults, giant-hurled boulders being similar in nature.
Strength Bonus Considerations: Here we have the first mention of what would later be known as "Strength bows," or in 3.x, "Composite bows" (composite bows were a wholly different animal in first edition, being simply just another type of bow). In first edition, a strength bow would grant the strength bonus to hit, as well as to damage, unlike later editions, where it only added to damage. Slung or hurled weapons, of course, always gain strength bonus.
Dexterity Penalty and Bonus Considerations: Dexterity "to hit" adjustment for missile weapons applied to initiative in first ed. as well as the actual bonus or penalty to hit an opponent.
An interesting thing to ponder: Does a strength bow then gain both the Strength and Dexterity bonuses to hit? This isn't clear in the rules, but would make, for example, a strong thief a very deadly opponent indeed.
Note regarding giant and machine missiles: A blurb reminding (or informing) the DM that giants or siege engines throwing great rocks don't allow targets their dexterity bonus to AC, as they are too big. Since earlier we were directed to the siege engine rules for Giant-hurled rocks...this bit probably belongs in that section, not here.
Missile fire cover and concealment adjustments: Here we have the basic % of cover and concealment translated into AC bonus for the target. Personally, I've always preferred to just translate the % cover into a straight miss-chance, with failure on the % dice indicating striking the cover, and the % concealment into a hide percentage (you can't attack what you can't see). It's an extra die roll, but it replaces extra calculation to determine whether you would've hit the target if not for the cover and blah, blah, blah, so it's a trade off. It also, as I mentioned earlier, makes for a very simple method of determining firing into melee.
Here we have the breakdown of damage and splash area for things like oil, acid, holy water, and poison. Interestingly, a character's strength has nothing at all to do with how far he can throw something. This always kind of bugged me; all thrown items have a range of 1/2/3".
Here we do get into what I think may be a bit of overcomplication, but what at the same time could add a lot of fun "Groan!" moments: when you hit with a grenade-like missile, you have to roll again on the item saving throw table to see if it actually breaks.
Splash damage extends out to 3' surrounding the point of impact. It's somewhat frustrating how Gygax jumps between inches and feet to identify areas and distance, though presumably measurements in feet denote that regardless of indoor or outdoor scale, that's the area/range/distance.
Once again here we have a reiteration that boulders have a 1' or 2' area of effect. More information is given that for every 14 lbs. of weight, 1d6 damage is dealt (or 1 point of damage per foot of distance dropped between 10 and 60').
A simple system is given for determining the direction and number of feet by which a missed throw misses. 1d6 determines feet, 1d8 direction. Easy and intuitive to remember, though oddly the d8 begins with long right (1:30) instead of straight ahead (12:00).
One more interesting tidbit: a reminder that unholy water damages paladins. Good stuff; I'd nearly forgotten that.