General guidance on Bat recording with AudioMoth

Dear AudioMoth-Team,

I've purchased an AudioMoth from labmaker last week and I'm waiting for it with excitement. If it suits my application, I'd like to order up to 50 more. Could you please give me a hand with following general questions (I've already screened the FAQ, the manual and some forum threads):

1. How long does the delivery from LabMaker to Germany roughly take?

2. I'd like to record Bat noises at a frequency of around 50kHz. According ot the Nyquist-Theorem, twice the sampling rate is required:

https://en.wikipedia.org/wiki/Nyquist%E2%80%93Shannon_sampling_theorem

That means, I will probably record at a frequency of 192kHz most of the time, which requires better SD-cards. I thought about going for a 400GB SD card with U3 speed for around 77EUR, which hurts a bit:

https://www.amazon.de/SanDisk-Extreme-microSDXC-Speicherkarte-SD-Adapter/dp/B07FCQRN9K/ref=sr_1_7?__mk_de_DE=%C3%85M%C3%85%C5%BD%C3%95%C3%91&dchild=1&keywords=512gb%2Bmicro%2Bsd%2Bclass%2Bu3&qid=1585474913&sr=8-7&th=1

Could you please comment if this is a good or bad idea?

3. I'd like to power the AudioMoth over 3.7V LiPo battery. Seems fine since the battery voltage indicator goes from 3.6 to 4.6V. What is the maximum rating? Where does it run most efficiently, around 3.6V for the MCU?

4. I'd like to use the AudioMoth outside in a temperature range of -10°C to 30°C. I will use an enclosure to protect it from rain. Is moisture, condensation or ice a problem at lower temperatures? Should the AudioMoth be sealed in a plastic bag like I've seen already? What is the effect of using a plastic bag on the audio recording? What frequency range does it affect?

5. When using an external Microphone, what do you suggest? There are not so many candidates:

https://www.mouser.de/Search/Refine?Keyword=ultrasonic+microphone

Knowles and InvenSense produce good ones.

Best and thank you!

Marco