Context
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Hello, I'm assembling a DnD/Pathfinder group, and all the players are new to tabletop rpg. All they know is rpg is about storytelling, dice rolling [ and macabre rituals <- just kidding, ;) ]

The thing is, I, as DM, find the D20 combat system pretty rich/interesting. I'm reading it all again, long time no play. Reading about the combat rules (flanking, line-of-sight, combat action/moves), it seems all a bit complex, without counting the combination of all of that together with class abilities, feats, spells and the multitude of options in the characters' creation and evolution.

The players are not into reading or maxing a character; from one point of view, this is a good thing, so we can focus on the role-playing. On the other side, they won't know all the options available, whether in the character creation and evolution or in the combat itself. So either we'd be playing a subset of the game, I would have to tell them all the options available, which I think might be kind of boring and could ruin the atmosphere.

Short question
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How can you introduce the game mechanics to new players, without telling them to read the books, or being a cumbersome boring DM, telling them what to do in the middle of the session? It could be some adaption to the mechanics, a method for introducing rules step-by-step. Or we could even try another system (a opened reference would be most appropriate). So, have you ever been in a similar situation and how to solve it?