Yeah, you should remove the saddle and turn that thing around, then re-attach the saddle pretty much level. I would not want to spend more than half an hour sitting on that setup. You may be able to simply loosen the nut and turn the part that is currently clamping the seat post 180 degrees to the front, no need to remove the saddle from the clamp.

Rule of thumb is this: If you turn the pedals to a horizontal position (let's say the left one facing forward), the part of the leg just below your kneecap should be pretty much perpendicular to the pedal's axis. If your saddle is too far forward or backward, you will not be able to pedal efficiently. It's probably part of the reason why you cannot go very fast since you're unable to use the leverage of the crank arms that way.

About saddle height: If your saddle height is correct, you can turn one pedal to its lowest point and place your heel on it. If your leg is then just slightly bent (shouldn't be straight, but not a significant angle either), you're probably pretty spot on.

As an avid cyclist, I can say that those are just pretty good rules of thumb. With my experience as a rider, pretty minor adjustments make a big difference and I tweak new bikes or parts as I go based on how it feels. I also learned from bad experience (knee and achilles heel problems from too high a saddle, for instance), so what I wrote above is a good starting point for you until you start getting a feel for such things with more kilometers under your belt. Welcome to the club, champ!