How many different 12-digit bit strings are possible?

For this one I did \(\displaystyle 2^{12}\) \(\displaystyle = 4096\) Different strings

What is the probability that a12-digit bit string has exactly five ones but begins and ends in zero?(Hint: Remember, all of the different 1’s and 0’s are indistinguishable from one another.)

What is the probability that a12-digit bit string has at least eight ones but begins and ends in zero? (Hint: break it up into cases)

The last 2 have me a bit puzzled as I am not sure where to begin. Could someone tutor me.