questions about crafting Guns/ammunition

[ShiningCrusader]

Hi everyone.

so i'm building a themed class and I noticed that the gunsmith feat allows you to craft guns without a Craft check. the campaign will be guns commonplace/guns everywhere, so a pistol would cost 250/100 GP and 125/50 Gp when crafting. here's my questions
1. is this unbalanced? all other melee and range weapons have craft DCs. shouldn't guns too?
2. if the Dm changes it to a Craft check, would the craft DC be that of a bows or crossbows?
3. if the pistol costs 250/100gp wouldn't that mean i could craft a pistol in less then a day? because its a day for every 1000 Gp the weapon costs when crafting.
4. this is sort of off topic but, do i even need adamantine/silver for level 1 maybe 2? if it unlikely that i'll be facing with those weaknesses, admantine/silver bullets are some what expensive and i don;t want to buy then unless i really need them.

note: me and the DM are new to pathfinder, we played a lot of D&D 3.5 and were not use to the classes and monsters getting nice things.

[Ninjaxenomorph]

You CAN actually use normal crafting rules; its technically cheaper except for ammo. If they are commonplace, it would be the same craft DC (standardized parts I assume). The Gunsmithing feat allows for gunslinging classes to not be stuck in the dust in places where they would not obtain better or different guns or ammo.

As for the material question, DR/adamantine is pretty rare to find early on, but silver isn't as bad an investment, though you can certainly put it off till possibly around the level 3 area. Cold iron is cheap, though, so a cheap cold iron weapon wouldn't be bad.