what does it mean if my total winnings are 1/8 of my showdown winnings? How would it compare to if my total winnings are 1/2 of my showdown winnings? Does a low total winnings rate compared to a much higher showdown winning mean that I am folding too much when I am ahead?

Having low overall winnings and high showdown winnings could mean you fold the best hand too often, but it could mean something else. Don't start calling more based on this alone.

More aggressive players will have higher non showdown winnings and lower showdown winnings. It also depends on those you play against. Loose passive players (calling stations) will cause you to have higher showdown winnings and lower non showdown winnings. TAG's will do the opposite.
Mostly it's down to your playing style.

There are probably others who know a lot more on the topic than I do.

depends on how you play. i havent put enough though into your game to really give you a good answer about this (or maybe i have and i just don't want to say. being the competition and all makes it hard to talk:) )

as for the folding, do you make calls like this?

Full Tilt Poker Game #11452468580: Table Pulsar (6 max) - $0.50/$1 - Pot Limit Omaha H/L - 14:39:01 ET - 2009/04/01
Seat 1: Lizzi29 ($35.40)
Seat 2: Zephyr ($149.40)
Seat 3: mobama1 ($40.75)
Seat 4: SMT Money 100 ($242.45)
Seat 5: antistuff ($312.45)
Seat 6: Icey Hot 9 ($97.85)
antistuff posts the small blind of $0.50
Icey Hot 9 posts the big blind of $1
The button is in seat #4
*** HOLE CARDS ***
Dealt to antistuff [Ac 2h 4c 5s]
Lizzi29 folds
Zephyr folds
mobama1 raises to $2
SMT Money 100 raises to $7.50
antistuff calls $7
Icey Hot 9 folds
mobama1 calls $5.50
*** FLOP *** [Qs 7c 3d]
antistuff checks
mobama1 checks
SMT Money 100 bets $23.50
antistuff calls $23.50
mobama1 folds

if smt money100 is at all aggressive (good or bad) and you are folding that flop then yes you are making bad folds. i will warn you, trying to add the whole "calling light" thing into your arsenal is very tricky. you can't really drop down to play with it because the players at $50 and lower are too nitty. so if you want to learn how to stack off with middle pair and be right you are going to have to do it at your normal stakes and its not what i would call and easy thing to get the hang of. if you can incorporate it correctly it will add a lot to your winrate though.

I would call or maybe raise in that spot. Any low card will probably give me freeroll outs. If the ace or 2 comes it could counterfeit someone and then I could easily take the pot by betting the turn.

i dont like a raise in that spot. your call is extremely thin in the fist place and you are speculating. i still think its definitely a call but its not like a call by a wide margin. and in fact if mobama had enough left where he could raise and let smt 3 town it i usually just fold. because of his stack size it becomes a HU hand (with benefits if he puts his money in).

just a random example of a spot where a lot of people fold and they should be calling. there are others, especially on the river.