Harry,
Some suppliers will have a kit (as 1 part number) to sell for all these needs. I would suggest finding a few kits for sale and comparing contents (based on vendor details, no on buying multiple kits!).
WRe,
What's labeled on the diagram at the bottom of that page, there are two holes down low labeled as "Plugs". Aren't those the outlet drain hoses for the heater box? Or the air inlet box? You know, the hose with the little bulb on the end? (Struggling to find a pic in our forums.)