The help file for pets says that they won't ever betray you. They will if you're suitably awful to them.

Beastmasters should probably start the game with full monster info.

Necromancers should probably be able to master shovel.

Where does it say that? I don't see that in either the salmiak help or the nightly help; on the contrary, they explicitly explain that pets require upkeep and may disappear or turn hostile if neglected too badly.

Verbatim, from Help: Pets: What could be nicer than a loyal pet? People sometimes worry their pets will trample them underfoot;

They will, and given the chance, they will remorselessly grind your bones into dust.

Temporary brand damage from craft magic isn't displaying on the character sheet for melee. It seems to display just fine on a shooter.

Does artifact reforging reroll an artifact's stats/effects guys? And what is the use of max power in reforging? And does it cost gold?

I've been playing in coffee-break for a while but I really haven't tried it since most of my runs get cut short in the late 30's to early 40's. Finally got a berserker to DLVL 54 though so I'm pretty happy with that x)

Reforging is pretty expensive. The max reforging power (determined by your fame) indicates how high-scoring an object you can use as the source item. Reforging does not keep any of the stats or bonuses of the source item, but does keep those on the destination item (note though that the destination item cannot already be an artifact or ego).

See the in-game FAQ (?d) for more details.

Quick question - how does Device skill impact damage from devices, if at all? When I look at the damage of (for example) a wand of magic missile, it seems the damage doesn't change regardless of my device skill (for example, taking on and off gloves with a device skill bonus). Does the damage really not change? Or does it change, it just doesn't reflect in the damage shown when you examine the item?

Small request, when you dismiss pets and it's says "x pets dismissed", it'd be nice to get the new upkeep value. It'd also be handy to have some way to tell which pets are hasted. Currently I have to stick numbers on hounds and spiders to tell them apart.

AFAIK, impact damage is predetermined when the magical device is generated and probably based on dlvl. Once generated, there is no way to increase impact damage.

Device skill has no effect on the damage or power level of a device. It is determined when the item is generated, and can only be improved by race/class specialities, super-rare +DevicePower egos and the Device Mastery spell.