for one. you dont need to drain the coolant, you take the hose off the engine and blow the core out, i just blow through it till it gets most of it out, that reduces the chances of spilling it inside the car.

2, the one clip that holds the core in is located on the fire wall, you need to reach up from inside to get it out. follow the pipes up.

3, that seal they are talking about is like thin foam too, handle it with care.