Seat height is determined by pedalling efficiency, and has nothing to do with being able to touch the ground while sitting in the saddle. To find the right height - put one heel on the pedal at its lowest point while keeping your pelvis square on the saddle. Your leg should be straight. It's a bit high if your pelvis starts to rock with each pedal stroke. Adjust the height in small increments, 1-2mm at a time. Too low and you'll only be using a fraction of your potential power and your legs will burn-out on the smallest of inclines. Too high and you'll be out of kilter - unable to maintain a respectable cadence and risk long-term injury.
The distance from saddle to handle bars should be comfortable, ie. not too cramped or over-extended when riding. It's hard to overstate how important it is to have the right size frame. When comparing different bikes the critical dimension is the effective top-tube length - the distance from the centre of the top of the headtube along a horizontal line to the point where it would intersect with the centre of the seat tube if it extended that far. Take a surf on the web to check how your current frame stacks up against other brands. Adjustment at the saddle compromises your pedalling position - best not to do that. The effective length can be tweaked with different length stems but this alters the bike's handle.
Riser bars, high-angle stems and/or spacers under the stem let you modify the relative height difference between the saddle and your handlebars. Lower bars are better for hill climbing, higher better for descending and more comfortable on your back. Modern frames with long travel forks favour a more upright stance - more couch than broomstick - so your handle bars will probably end up at a similar height to your saddle.
Once your basic stationary set-up is sorted it's time to jump on the beast for some real-world testing. Bad habits, old injuries, tight muscles and fragile backs can throw a spanner in the works. Do your knees act weird at the top of each pedal stroke? Maybe your upper body bobs to maintain your cadence or to smooth out your pedal stroke? You may need to tweak your set-up or possibly change the way you move. The Alexander Technique preaches that you can beat your body into submission, wear hair shirts and practise the correct movement until it becomes second nature.
Correct gear selection and therefore a strong, even cadence are synonymous with good form. 80-90 rpm (higher on the road) should land you in the same bunch as Gunn Rita. Drills of one legged pedalling (for 3-5 minutes) teach your body volumes about spinning in fast, smooth circles.
Spring is the time to re-assess your technique and bike set-up. It's highly likely that your training-log is looking a little thin - your hamstrings will have relaxed enough to let you tie your own shoelaces and test your body in subtly different positions. Allez Allez.