DIRECT STUDENT LOAN

I have about 43k in student loans, one loan is 8.75% and the other is 5.34%. I figure I have about $750 a month I can either put towards the loans. My question is should I put all of that towards the loan, or put some of it in savings?

I have borrowed more student loan money than I should have, around 50k, and I need to know what are the steps in getting low payments and who to get them consolidated with?
Also what should I expect as monthly payments to pay it off in 20 years? And in 30 years?

I have paid about 1200 this year to my student loan. What do I need to make sure to do? I graduated college ions ago, but I want to make sure I take advantage of tax breaks out there. I know this is one, but I’m not quite sure how to proceed.

My grandfather co-signed a private student loan for me. Now that I am done with school, I am the one paying off the loan but since my grandfather co-signed it shows up on his credit report and not mine. Is there anyway for me to get this added to my credit history? Or is there something else I can do for the future, if necessary, to show that I have actually been making the payments and not my grandfather. Thanks!