Luck influences a bit anything you are doing in the game. So you can see even probability of successful casting increase along with increase of Luck, so do chances to hit or to avoid being hit, even probability to make successful bribe and how much the bribe would improve NPC's attitude to you.
Speed is also about how fast you move (you are familiar with BoBS, aren't you) and how fast you hit (in lesser degree just for technical reasons). It's also the base for the Athletics, Unarmored and Unarmed skills to depend on. In fact the movement speed depends on Speed Attribute, IMHO, almost completely, and Athletics skill rather determines how much Fatigue you're going to spend on running or swiming.
Personality in first place could improve NPC's attitude to your PC. There's the basic value calculated by racial, factional and , as it's said though the impact seems to be minor, appearance factors, Personality adds up over that. It's also important for Illusion, Speechcraft and Merchan skills, boosting Personality may help to compensate the lack of the skill. Be cautious with Personality boosts in communtication with NPC, though - if you'd used it and then returned without the boost it's quite possible that they'd like even less than it'd be normally (nobody likes to be deceived, huh?). Knowledge of this fact could be altogether used for certain profit (there
are few occasions you'd like certain NPC just to hate you, aren't there?)
P.S. Manual contains just basics - sort of controls, how to use them, very general description of races and profesions, main concepts a bit defines and so on. Nothing much specific and numeral, however, you could, for example, gain a lot more information about races here on GameBanshee
Morrowind pages
You might wish to see also
Morrowind Unofficial Strategy Guide by Stratos Group.