1) Yes, but that is also because all classes that use a bloodline alter the bloodline your character possesses. If you add Sorcerer/Bloodrager or Blood Arcanist to a character with a Bloodline you must select the same bloodline for all classes. This may include retroactively changing your current bloodline to whatever you chose for the new class, and thus your current bloodline powers, spells, ect would all be altered to fit the new selection.
The exception to this is Eldritch Heritage which specifically says you gain a power from a second bloodline, and its the first level ability. So you would have 2 first level abilities, and then any other bloodline abilities you would gain from class levels.
And the final thing to say is if you had Eldritch Heritage you could trade away that 1st level ability instead of your main bloodline's 1st level ability to get Blood Havoc. You could eve trade it away twice to get blood havoc twice, but since its the same ability it will not stack with itself.
To gain Intensity and Piercing you'll need to trade away your higher level blood abilities as specified.
2) Both of them say what level sorcerer you are considered. Blood archanist is going to share the same bloodline as sorcerer and bloodrager anyways. Only Eldritch Heritage introduces a 2nd bloodline to your character.
