So the question:
Do I understand correctly, what if I as Arcanist will choose this feat "Bloodline Development" twise I can progress in Blood Line abilities as i rise my Arcanist Lvl?
as exmp: If i am Arcanist 20 lvl, with 2 feats in bloodline i will be immune to age & do not need drink/sleep/eat? permamently without need to use arcane reservoir points?
https://www.d20pfsrd.com/classes/core-classes/sorcerer/bloodlines/bloodline s-from-paizo/imperious-bloodline-sorcerer-human/
She does not gain any other abilities when using this exploit in this way, such as bloodline arcana or those bloodline powers gained at 3rd level or higher.
That exploit only gives you the first level bloodline power of that bloodline.
For example,
Student of Humanity (Ex): At 1st level, you gain Diplomacy, Knowledge (history), Knowledge (local), Knowledge (nobility), and Linguistics as class skills. In addition, when using these skills to learn, study, or gather information about humans, you add an insight bonus equal to your Charisma bonus on such checks.
If you took one level of sorcerer, then the other 19 of arcanist could indeed work towards advancing the entire bloodline. But being a spell level behind is very hard on the leveling character.
If the arcanist already has a bloodline (or gains one later), taking this exploit instead allows her arcanist levels to stack with the levels of the class that granted her access to the bloodline when determining the powers and abilities of her bloodline.
Bloodline Development is not a feat, it is a Arcainist Exploit. You cannot take the same exploit more than one. That also applies to feats as well unless the feat specifies it can be taken more than one. Usually, the only time you can take a feat is when it is something like weapon focus that only applies to a single weapon or something similar. Even then they do not stack.
thanks!