Need advice on: Lian Li tu 150x and Be Quiet Dark Pro 4

[LJA]

Hi people.

I've just bought a Be Quiet Dark Pro 4 to use with my current Lian Li tu 150x.

My rig:

. 3900x

. Asrock B550 PG itx

. Corsair LPX

. Radeon 6800 Reference Model

So I have some doubts that I need advice:

 

1. Should I install the cooler outside the case? I think that might be easier to connect the fans that way and I've heard that is not exactly as user friendly as Noctua securefirm is, but I might be wrong.
2. Is it possible to plug the Front Panel USB cables with the front fan installed? or I might be running into some space issues? (I've already had issues when I had a Noctua d15 with the USB3 and the USBc ones, this BeQuiet kind of looks like maybe evvn more trouble). Does the Cooler loose too much of its perfoamnce If I'm not capable of installing the front fan? NOTE: I can't buy USB angle adaptors, I live in Argentina and it tooks too much time and end being extremely expensive, specially when all of them look to have a poor quality.
3. I've seen that it gets really close to the back fan, I've already have there a slim Noctua one, should I keep it? is it necessary? or should I replace that one with a normal 25mm Noctua Nf-F12 (I know is more oriented for heatsinks)? I don't know if the differences in speed and airflow from the different models of fans involved might not end being counterproductive.

 

Well that's all, thanks in advance! and pardon my english since it ain't my first language. BTW any extra advice would be more than welcome too!