Denizens of the Undermountains
Reading about the Dwarves in the Core Rulebook I am getting a sense that Dwarven society is a very closed society. And they are a closed society because the Dwarves are a beleaguered folk; in a state of perpetual war in their underground and inner mountain fastnesses. This apparently endless struggle has defined them as a people and should define any Dwarven adventurers you create.
The write up goes on to state that Dwarven adventurers are rare. It makes sense, the Dwarves are committed to their kingdoms. Wandering around in search of adventure isn't in the Dwarven DNA. The reasons a Dwarf would go on an adventure as stated in the Rulebook are (1) to win wealth for their dwarven citadels, (2) to win reknown for their clan and (3) to reclaim a lost real (a la Moria in The Lord of the Rings). Notice a common thread in all these reasons? Home. I would suggest that any Dwarven adventurers you create should always have home in mind.
Defined By Their Enemies
Most Dwarves are said to be Lawful Good. The alignment of a good citizen. A conservative who values his place in society. Why are most Dwarves Lawful Good? Because lawful good alignments make up the most solid unions in society and Dwarves survive by being united.
United against what? You ask. Their enemies. The Dwarves are defined first by their realms and their kind and secondly by their foes of which there are three primary ones: Goblins, Orcs and Giants. Their long running feuds with these races have made them expert fighters of these named foes. Dwarves get a +1 when attacking Orcs and Goblins. Giants are simply too formidable for Dwarves to get an attack advantage against them but Dwarves do get a +4 when dodging Giants because of their skill and their size. Speaking of size . . .
The Logic of the Dwarven Physique
Why are Dwarves around 4 feet in height on average? The answer is because being short is advantageous when you live underground. But short is just the beginning. Let's look at the Dwarven physique.
The ideal physique for living underground. In particular look at the calf area. Very thick - this guy will never get a sprain. In fact Dwarves get a +4 CMD when being bull rushed and tripped. Makes sense, the low center of gravity and muscular stocky build would be hard to unbalance.
Favored weapons are battleaxes, warhammers and picks. The picks would be tools as well as weapons so it makes sense that Dwarves would be used to this. Between battleaxes and warhammers I would guess that Dwarves favor the latter. Jostling around in those tunnels it would be easy to cut each other with bladed weapons but they can bump into each others warhammers without injury.
Dwarves as PCs
Hmmm. So Dwarves as PCs. I'm really partial to this dour, tough race but having read about them, yes, any Dwarf PC I create would have to have a really good reason for being apart from his people and also being up there in the unnatural environment outside of the heart of mountains.