Character Classes are very important in Diablo. Each class has it's own strengths and weaknesses making them suitable for play, but the style of play will vary greatly from one type of character to another. The type of character you choose will depend upon how you want to play Diablo. If you are and in your face, up close and personal type fighter then you might want to go for the Warrior class. Then again if you are more the type of character who likes to stay back out of the action and just blast away with spells, then perhaps a Sorcerer might be more to your liking. However, if neither of these are to your taste perhaps something in the middle like the Rogue character would be what you should consider.
Miscellaneous Character Stats
Gold
Once a moderately valued commodity in Diablo, lately on Battle.net this particular substance has almost no value. An average high level character can get 200K on the higher difficulties with between a half hour and an hour's worth of work. Not to mention the fact that cheats that allow people to create unlimited amounts of gold have also brought it's value down.
Armor Class
Armor Class, (a.k.a. AC) is a measure of how much protection you have from being hit by an attack. This protection comes from better Armor, high DEX, and magic. The higher your AC, the harder it is for people and creatures to hit you. AC can be raised by using magic items that increase DEX, better Armor, better Shields, and of course wearing a Helm. AC does not seem to have an effect on magical attacks like fire, lightning, and spells. Also, arrow seem to be able to penetrate armor better than regular weapons.
To Hit Percentage
This is your ability to hit an opponent with no armor at all. Basically the way this works is your opponents AC is subtracted from your To Hit Percentage and that is how likely you are to hit them. (For Example, Your To Hit Percentage is 123%, your opponent has an AC of 75. This means your chance to hit that opponent is 48%. If your opponent had an AC of 0 then you would have had a 123% chance to hit them). This can be raised through using various magical items and increasing your DEX.
Damage
This is the minimum and maximum amount of damage you will do if you actually hit your target. This can be raised through using magical items and by raising you STR.
Resist Magic, Lightning, and Fire
These 3 values max out at 75%. They are a measure of how much resistance you have to each type of attack. These values can only be raised through the use of magic items. They really become important once you start to enter the caves and hell as that is when you start seeing monsters that can cast spells and spell-like effects at you.
Sorcerer
Warrior
Rogue