First of all, let me say congratulations for making the decision to change. You've come to the right place. There is tons of information here at T-Nation to help you rebuild your body and get into shape. I also congratulate you for posting your goals. You're much more likely to acheive them when you write them down. Also the fact that you posted them in a public forum adds to your accountability. Yep, that means we're going to expect you to follow up with results. Anyway, on to your questions:
I would suggest looking at Vroom's "Are You a Beginner?" thread
That should give you some good ideas to start with. After you've read through that, feel free to ask questions about any specifics.
You can use lat pulldowns until you are strong and/or light enough to do bodyweight pull ups. Just like regular pull ups, when doing pulldowns vary your grip. Use wide grips, narrow grips, palms facing up, palms facing down, etc.
If you can't perform dips, try doing bench dips. You can probably search for an exercise description. They are listed as one of the warm-ups in Ian King's 12 Weeks to Super Strength Part III article which can be found here:
...place two benches about one meter apart and parallel. Sit on one and place the feet up on the other. Slide your bottom off of the bench but keep the hands on, with the fingers pointing toward the feet and curled over the side of bench.
Using your triceps, lower the hips down as far as comfortable, then raise yourself up, stopping just shy of elbow lockout.
Also, there are a variety of pressing motions that you can do, rack lockouts, close-grip presses, floor presses, board presses, etc.
Hope this helps and keep us posted on your progress!