Tweethey bud, it depends where do u get ur kit from. I think chem's kits are 100mg/ml. so u gota ask the site that u bought ur kit to find that out.
as for the pain, again it depends on how u made ur tren, some times it hurts some times it doest, but usually its painless. and yes i would rotate so u wont have any scartissue build up there, just rotate from gluts / thighs /delts.. nice and painless. take care