1.  Great choice on case. 
 
2.  Your choice of components look good but I personally like to go with 240mm since the 120mm seem to perform better on rads than the bigger 140mm but that's just me.  If you like the 280mm, that's fine too. 
 
If you change to 240mm, the only thing I might change are the fans to something like Noctua A12 (Newest) or Gentletyphoons as those are the powerhouse fans for rads if you're looking for every degree possible. 
 
If you're looking for bling, that's cool too with fans like Corsair's LL120mm.  I just swamped my top rad fans out along with the rear fan for aesthetics and so far so good.
 
3.  For the OS drive.  I would jump on this Samsung 970 EVO 1TB ASAP since it's almost 50% off and it's Samsung, best in the business when it comes to flash memory.
 
4.  Should have no problem connecting all your drives to your SATA ports.
 
5.  There's a good chance any Z390 MB that will come back to stock will and should have the most up to date BIOS in them.
 
6.  As far as PCIe Lane breakdown, I'll leave this image below to give you an idea what you have in store.
 

 

 
Depending where you install your M.2 PCIe OS drive, M.2 PM1 or PM2, your PE3 lane could be disabled but than again, you'd be leaving your M.2 under your probably pretty warm GPU.  I personally would go with something like this.

PE1 - RTX 2070 (x8)
PE2 - Empty
PE3 - Empty (Disabled because you installed your OS Drive to PM2, on the second M.2 interface away from the top
PE4 - Sound Card (x4)
 
Whether your GPU is x8 or x16 honestly, won't be performance degrading unless you're running 8K+ with high refresh rates which atm afaik, aren't in existent and the GPUs wouldn't be able to handle that kind of content anyways.  
 
You should see some more in stock eventually I think but don't forget, their next 'Z' line from intel and eventually from EVGA will be out this fall iirc.
 
Hope that cleared a few things for ya and also don't forget, you can use a associate code as seen in my signature to get a bunch of discounts on a variety of hardware and purchases EVGA's store.
 

Man that's some good info!! I downloaded the manual for the Black earlier and tried to read through it and my eyes crossed, this points me right where I need to be!! thank you!!
 
I have a Hauppauge Win-Tv HVR 2250, had it for YEARS now and I can't live without it, that is a must!! The sound card I MIGHT be able to do without IF the sound in the Black is decent, I will have to see.
 
IF I can use 6 SATAs and the M.2 I can leave the add-in SATA card I'm using now out of the build, so that leaves me with:
 
RTX 2080 x16 (preferred)
(the M.2 space under the card)
1 TB M.2
Zx Sound (if needed)
(Disabled)
TV card 
 
THIS is the ONLY thing I don't like about the dark is the shortage of slots, (BUT...it's just so sexy I gotta have it!!) I'm gonna need slots PE2 and PE4, for sound and TV. (or at LEAST TV), and the M.2 cancels PE3...and that SUCKS...BUT I have my SATA's soooo
I think it will work IF I can use at LEAST 4 SATA ports, prefer 6 for my storage tray!!
 
I'm selling my other parts for the drive(s) SO I have to wait for the Black to come back in stock or I will be out of a PC till it does (I'm gonna MISS this Classified Z270, it's been a ROCK)....SO I may have to hit the plastic to get that Samsung M.2 on sale!! (I hoped to do it all with cash but..,..duty calls)
 
 
 
As far as the cooler goes, I already have the 280mm on my desk, I was thinking bigger would be better, I guess I can always upgrade the fans if needed, HOPEFULLY I won't "need" to overclock this CPU that much *cough* as it looks like a beast, I could care less about the colored lights, Black is just fine with me!!
 
 
TV = IMPORTANT
High grade Sound = VERY important
(I use this PC for EVERYTHING)
 
 
  
I THINK I'm good guys, THANK YOU VERY MUCH!!
 

The Z390 Dark will have support for the I9 9900k for sure as the bios that came with release version already had it.
I had a Creative SoundBlaster Z in my previous rig, and personally I found the onboard Creative Sound to be pretty darn good, so I never bothered to install the Z into this rig.

Have you considered a USB TV card?  I ran multiple Hauppauge PCI cards in my old BeyondTV Server back in the day.  The newer USB options have improved over the years.  Or, entertain a kick-butt USB DAC/Preamp better than the NU card.  You will need to sacrifice audio or TV card if you want x16 for GPU.
 
 
BTW, sad news about the fire...  pics were horrible.  

GTXJackBauer

808sting
 
BTW, sad news about the fire...  pics were horrible.  

https://www.kentucky.com/.../article232251777.html

808sting

GTXJackBauer

808sting
 
BTW, sad news about the fire...  pics were horrible.  

https://www.kentucky.com/.../article232251777.html

Oh yeah, heard about that.  That stinks.