Character Hit Points: This is a pretty basic coverage of what hit points are and how they work, but there are two points of interest here that I'm not sure have been covered earlier.
The first is that monks and rangers have two hit dice at 1st level. I've never actually considered this, but for the purposes of spells and other magical effects they should count as 2HD creatures. I've always treated characters according to their level, but in doing that I've probably been short-changing monks and rangers.
The second is that Gary tackles the most common complaint about the hit point system head-on. Invariably when discussing D&D and RPGs in general, there's always some ning-nong who talks about how ridiculous it is that high-level fighters can survive a hundred sword wounds. Well, Gary agrees with you, and that's not how hit points work. His description of how they do work is as follows: "the majority of hit points are symbolic of combat skill, luck (bestowed by supernatural powers), and magical forces." The explicit mention of supernatural powers influencing hit points says a lot about default AD&D, and could perhaps tie in with the alignment stuff I was talking about in my last post.
It's mentioned that rest restores hit points, but no figures are given. The idea of keeping a character's exact hit points a secret is also brought up, and I'd like to recommend that DMs try it at least once. Players can get extremely cautious when they don't have the exact numbers in front of them, and it adds a lot of tension to the game.
Establishing the Character: At this point Gary recommends naming your character and creating a family background. (Which is odd, because I'm sure I've read somewhere that a lot of characters in his campaign weren't even named until they reached 3rd level.) He also mentions the idea of naming a next of kin that can inherit your character's possessions in case of an untimely death, which is a rule from OD&D that I feel gets little play in later editions.
What's of most interest here is that we get a glimpse into what I assume is what Gary sees as the quintessential campaign opening scenario. He described the characters approaching the main setting (probably a village, town or city), getting through the main gate, finding a place to sleep, and learning the lay of the land. Again, it doesn't feel quite right given what I've read of Gary's DMing style; I would expect him to get to the adventure a bit more quickly. Still, it jibes well with two of his introductory modules, Keep on the Borderlands and Village of Hommlet, and it could be a difference between starting an adventure and starting a campaign.
Character Languages: The first thing established here is that all humans, semi-humans, and non-humans in regular contact with people speak the "common tongue". The use of parentheses here indicates that "common" is not a language per se, but just a placeholder for whatever language would be appropriate in your campaign. Gary then says that common is spoken by all states in the central campaign area, which I will assume applies to Greyhawk.
Alignment languages are then discussed a little further. They can be spoken by all creatures able to converse in speech, which is an important qualifier. It rules out True Neutral characters having conversations with horses and oozes, for one thing. Importantly, it's noted that in most campaigns open alignment speech is a serious breach of social etiquette.
The process of learning additional languages is brought up. It requires the character being in close proximity to a tutor for a period of 12 months, modified downwards by high Intelligence. I'll assume that the character will still be able to adventure during this time, it's just that he or she can't go on any long trips, and has to spend a lot of downtime doing the learning.