1.) What external microphone would you recommend? Does the mic hook directly into the pre-amp and then into the cameras xlr-mini? I am new to this so trying to learn on the fly🙂.
Best option is to record audio externally and not worry with the camera audio (except for using it to sync up the externally recorded audio). I'm really not a fan of the BMPCC audio, so I try to personally avoid it as much as possible and recommend others do so as well.
Mic choice comes down to budget, types of settings you'll be shooting in, skill level, and expectations.
But if you want something that is decently priced, pretty fool-proof, and simple to use then I would probably recommend something like the Tascam DR-10L Belt Pack Recorder and Lavalier System (affiliate). Your subject wears the belt pack and microphone and the belt pack records the audio. It's a super popular option for "one man crews" and event/wedding videographers because of its simplicity.
If you want to just run audio through the camera to save time and hassle during editing, then you may want to check out options like the Rode Wireless GO II (affiliate) with the Rode Wired Lavaliers (affiliate). This will allow you to run a cable from the receiver directly into the 3.5mm input on the BMPCC and will also give you the ability to record internally on each of the 2 transmitters so you have an extra backup recording.
2.). Do you have a short video or one to recommend that would show steps in this setup and how to hook everything up? Trying to make sure I get all the equipment I need to learn and do this well🙂.
The two options I mentioned above are pretty straightforward and will be much simpler than using external preamps or recorders and extra microphones.