I agree with both points, Language would evolve way too fast for there to be any commonality after thousands of years, I imagine currency would be fine until a war broke out and with shifting conflicts eventually everyone would have their own style, it is based on how the world and group works...
I like the idea of having several components buyable but with only a shortage of money to stop them the players may very well just say "where's the nearest ancient ruin" or "where's the nearest person in need of help" so I will be prepared for that

the merchant will be gone or the item sold out when they come back
EDIT: Any tips on creating a CR 1 Large Crustacean, maybe with 4 Skeletons, two Warriors (Scimitar/Rapier) and 2 Warriors (Shortbow), they are dead pirates so I dunno how to customise them weapon and feat wise but the Crustacean is completely unknown...
EDIT 2:
Crustacean CR 1 (HD 3)
N Large Magical Beast/Animal;
Init: -1;
Senses: Listen +4, Spot +0;
AC: 12,
Touch: 8,
Flat-Footed: 12 (10+4-1-1)
HP: 30;
Fort: +5,
Ref: +2,
Will: +1;
Speed: 40 ft. (8 squares);
Melee: Slam +3 (1d6+4/20x2);
Space: 10 ft.;
Reach: 10 ft.;
Base Attack: +0;
Grapple: +3;
Attack Options: Constrict (1d6);
Abilities: Str 18, Dex 8, Con 14, Int 2, Wis 10, Cha 10;
Skills: Jump +7, Hide+3*, Swim +7*, Listen +4;
Special Abilities: Racial +4 to Swim, +8 to Hide in rocky underwater terrain
First draft, thoughts?