remember: Chicken poop is good fertilizer! :)
Normally I'd say baby steps, but you already have the chicks.
When you get around to it, take pictures of the equipment.
I bet the locals on BYC can identify it for you (and help you instructions for the doors)
In that case, use a garden sprayer.
The folks here on BYC have some preferred disinfectants. Generally, hot soapy water works for most household problems. You might have to walk a few buckets down to the coup! I generally clean with Ajax dish soap, but step it up on occasion. Just be careful...
a beginner myself, in your case I would go with 'thorough' right now: poop and feather removal and a good scrub with a decent cleaner/disinfectant.
Just to be safe.
There might be some elbow grease involved (perhaps done masks to not inhale any sh*t?)