I have two questions about using the fraction function of the TI-84 Plus CE.

1. What is the fastest (least key presses) to access the fraction sign?
Now I go alpha/y=/1/enter to access n/d. Coming from Sharp that has a fraction button I find Ti84's mode quite slow. Is there a faster way to access fractions?

2. How can I use a previously (but not just last) calculated answer in the denominator (bottom fraction part)?
If I use the arrow up key/enter to "move" the value in my current calculation it only places the value in the top fraction, regardless if the typing bar is in the denominator. I know I can use ans but that only works for the last answer.

1) If you're on OS > 5.3.0, you can do alpha X,T,θ,n. If your OS version is lower, then your way is optimal.

2) There is no "easy" way to do that. You could store it to a variable and then recall it using RCL (2nd+sto->)
It might be easier to write your fraction "upside down" and throw a "⁻¹" after it.