Now this may seem like a silly question for the astrologically advanced...but I've heard that Saturn is about to enter Libra. Now, according to my natal chart my saturn is in libra at 29 degrees in my 5th house. 

I'm only 26 (soon to be 27)...does this mean I'm about to experience the infamous saturn return?!? I thought it was when you hit 29 years old? Am I right? Also - I've already been hit with an awful last half of the year...does this mean more trouble ahead?   

You don't have to worry about your Saturn Return for some while yet; it's a return because it's when Saturn hits the same sign and degree as it is in your natal chart.  You won't start feeling the effects until Saturn hits late Libra, though it depends on how sensitive you are as to exactly when.  Personally, I feel big transits from way out, but as compensation I feel the release almost as soon as they pass exact.

I haven't done it, but you can cast a return chart for almost every planet (unless they're reeeeaaally slow).  I have no clue how to interpret them, though.

Thanks!! I think I'm like you where I can feel effects of planetary shifts way before they begin...I have that animalistic 6th sense I guess. yay for us, right? :)