Hurri Hot Heaters

[Eight24]

Hello Everybody!

I am once again asking for your help / input... this time, it is for removing the Blue Bird Hurri-Hot Heaters. (pics attached)

I found the two valves for sending and receiving the fluid. The first valve was coming off the engine and was obviously easy to find. The second valve required me to crawl under the bus. The second valve (the return?) was feeding into some other unit/box that also has larger lines running to the turbo.

So my questions are:
- Is my understanding of the above correct?
- Can I just turn off these valves and that's it for the heaters?
- Can I drain the lines that are inside the bus and that doesn't affect the turbo or engine or anything else?
- I'll need to remove the front heater too or can I hook that up without the other two Hurri Hot heaters?
- What is the name of this thing I circled in yellow?

Thank you for the help!