I think your idea to do 2 and 3 at the gym is a good one. The biggest concern I would have, is your weights just really might not be heavy enough at home, especially for meso 3. I would not worry about the slanted risers too much, I suppose you could just do more flat bench presses maybe just change the position of your hands to get a little difference in the muscles worked. But if you go to a gym for 2 and 3, I don't think you even need them in meso 1.
You don't need a squat rack, it's only needed for meso 3 legs IF you choose to do the heavy weight dvds for meso 3, I used the plyo leg workouts for legs, which are really great. You will need a step and dumbbells for plyo legs.
Also, to replace the chin up bar, you can use tubing (get a thick one) with an over the door thing that allows you to attach the tube to the door and do pull downs that way. I bought the Cathe tubing specifically because it comes with the little over the door thing.
The 1 rm testing will get your exact numbers, so there will be a lot of odd numbers that just don't conform to standard dumbbells, there are some options if you want to be exact, like 1 and 2 pound weighted gloves and wrist weights, a lot of people have plate mates (little add ons) but your dumbbells have to be the iron kind, not rubber or the kind with fabric. These are great for at home workouts, personally, I don't think I would bring my wrist weights with me to a gym
Good luck and have fun!