hi
the age isn't 18, it's 21, so if your parents are LPR one of the should file immediately, so she comes before she is 21. even if she was over 21, it will always take less than if you were to file for her
hi
your father is going to be your joint sponsor, as you don't live with him now in the US, you have to live in the same household for your father to be a household member
hi
not at all, a person can have more than one petition at the same time, the only thing is that you will loose the money since you won''t be continuing that petition, but other than that, no problem
hi
neither of them, those are forms to adjust status in the US so neither of there are for your process
they aren't online and you file the i485 with the i765 and other forms when you are adjusting status in the US, if you qualify to do so