grades

They all will depending on your other qualifications. There are no hard and fast rules for receiving a bid. Every sorority has different voting strategies and every sorority is looking for different qualities. Every sorority has different nation rules as well that state what gpa's must be. Some have gpa requirement in order to be initiated. If you are a grade risk, then they might be afraid they won't be able to initiate you if you can't keep up with the demands of college.

If you have no connections or nobody fighting for you in the house, then, yes, you will get cut for grades early. It's the way sororities weed out girls they don't know. If you are amazing everywhere else and can benefit their sorority in other ways, then they might overlook your grades.

It is very hard to tell and there is no way you will find the answers you are looking for on here.

there is not enough information. A lot depends on whether we are talking about a 2.9 or a 2.5 GPA. As you get closer to 2.5, the chances of getting a bid are just about zero.