Just jumping back to the pull-ups thing, I had the same problem, was absolutely crap at them when I started training for PRMC. The best thing I found was an assisted pull up machine at the gym; basically a bar, with a second bar at foot height that you stand on - this one moves, and you alter the weight on it to assist you, ie. you can take up to 80kg off your weight (if that makes sense). This way you can keep correct form for a good amount of reps and slowly build up to doing it with no assistance. I worked in 3 sets of 10, started using 45kg assistance (I only weigh 70kg!!), within three months could do the three sets completely unassisted. Lat pull-downs will help, tho not quite so effective as it's a slight variation on the theme.
Press-ups, vary your routines, use pyramids, 10 down to one, sets, maxes, wide arm and narrow arm, etc etc. You should see measurable improvement every week.
