KLEB

Yup should be fine. I've run 3 HDDs off a triple sata cable and they are way worse for drawing power than RGB hubs and a commander pro.

Yes, you can just attach them all on one cable.
 
The cable is only for power. No need to attach to motherboard.

Yep, just get yourself two of that 2 pack and you're all set for fan headers
I do have to kind of warn you, cable management can be a bit of a hassle. Of course you have 8 fans, which have a total of 16 cables (RGB + fan cable), going to two hubs, which goes to a Node Pro (which all have SATA power input), etc.
So do get yourself some twist ties and allow yourself some time to properly manage all the cables away.
 
One of the fan headers on the motherboard is kind of out of the away (the green header on the left side of the board). It may be easier to not use that one and instead use the leftover CPU_OPT header that is on the top of the board. That way you don't have cable dangling basically in the middle of the case and can properly route the cables in the back tray.
 
Both the RGB fan hubs + Node Pro need SATA power in, which comes from your PSU. 
The wire on the Node Pro, on the right side of the picture goes into the USB 2.0 header of your board. If you look at the picture/diagram of your motherboard, that is one of the two connectors on the bottom right, marked with the '15'.
 
Glad to be of help to you, if you have any additional questions, I would be happy to help!

Oh, so you're going for 6 LL120 fans and 2 fans on your CPU cooler (Noctua)?
Then you need to connect it like so:
You have most of what you need, you just need to get two fan splitters, so you can connect 6 fans to the 4 fan headers on your motherboard.
Then you also need to connect your Noctua cooler's fan to the motherboard, which your motherboard has two places for.
 
You connect all the fans (the green wires in the diagram above and your Noctua fans) here:
 
For 8 fans you will need this setup (which requires an extra two fan splitters):
 
EDIT: I feel like I should mention I didn't make these pictures from scratch, but took a picture from Zotty's excellent post over on the Corsair forum and edited it to fit OP's case:
https://forum.corsair.com/v3/showthread.php?t=173880

For most people 1TB is more than plenty of room to store all games and other items.
Adding a HDD later is super simple though, so I wouldn't worry too much about that too.
 
Some SSD's get slower when you are using 70-80% or more of the drive though

its always good to have a hard drive to store photos etc.
Or ssd whatever works
 

No reason you can't just use an m.2. Unless you eventually fill it up. You then have 2 choices.
Delete stuff from the drive.
Buy a new SATA Drive.
I imagine you'll be a while before you fill up the drive.

So you are only using your m.2 drive?
If so then you don't need the cables plugged in. But keep them in a safe place for expanding storage at a later date.

Yes.
Nope, you don't need to plug them in.
 
When/if you add more storage (HDD or 2.5" SSD) or an optical drive, you might need those cables, so do hang on to them.

I think going all out and purely focusing on performance is your best bet. If you do so you can get an RTX 2080 Ti. The motherboard you chose is nice to have but won't provide you with better performance, the budget can be utilized a bit better like so:
PCPartPicker Part List Type Item Price CPU Intel Core i9-9900K 3.6 GHz 8-Core Processor $523.89 @ B&H CPU Cooler be quiet! Dark Rock Pro 4 50.5 CFM CPU Cooler $89.90 @ Amazon Motherboard Asus ROG STRIX Z390-E GAMING ATX LGA1151 Motherboard $238.42 @ Amazon Memory G.Skill Ripjaws V Series 32 GB (2 x 16 GB) DDR4-3200 Memory $138.99 @ Newegg Storage Crucial P1 1 TB M.2-2280 NVME Solid State Drive $112.99 @ Newegg Video Card EVGA GeForce RTX 2080 Ti 11 GB Black Video Card $1089.99 @ Walmart Case Phanteks Eclipse P300A Mesh ATX Mid Tower Case $49.99 @ Newegg Power Supply Corsair RMx (2018) 650 W 80+ Gold Certified Fully Modular ATX Power Supply $109.99 @ Newegg   Prices include shipping, taxes, rebates, and discounts     Total (before mail-in rebates) $2364.16   Mail-in rebates -$10.00   Total $2354.16   Generated by PCPartPicker 2020-02-14 00:26 EST-0500   1. You can easily afford an RTX 2080 Super or 2080 Ti if you utilize the budget better.
2. Get low profile RAM, the G.Skill kit I added is fast, works with Intel out of the box and is the best price for a 32GB 32000MHz kit. I too prefer large air coolers, I added the Dark Rock Pro 4 because it is $10 less, and performance is nearly the same, spending $10 more on the NH-D15 is fine though.
3. For an SSD I added a 1TB NVME drive, in terms of $/GB it is not much more than a good Sata SSD/M.2 so an extra $15 spent here is fine. 650W is enough for you system the Corsair RMx is a quality PSU, meaning it is made with good components ensuring you don't have a PSU failure that can damage other hardware in your system as well.
 
The P300A is a great case for the price, the mesh front panel means your hardware can get cool air, unlike most cases these days, and it still has a nice tempered glass side panel.

Hello, I do not have much knowledge in this field, and I'm trying to build my own gaming/streaming PC for the first time.
My budget is around $2000-$2400, not including a monitor or a keyboard.
I have chosen about half of the components needed to build my PC and I'd like to see some feedback / suggestions.
 
CPU: Intel Core i9 9900k
Motherboard: Asus rog maximus xi hero
GPU: Rtx 2070 Super (maybe upgrade to 2080 super)
RAM: Corsair vengeance lpx 32GB(2x16GB)  3200MHz  (maybe Corsair vengeance RGB Pro 32GB)
CPU Cooling: Noctua Nh-D15 chromax.black  (I prefer this huge air cooler to other liquid coolers)
Storage: TBD
Power supply: TBD
 
I also have a few questions / concerns about this build:
1. is my overall build balanced? any component to upgrade to pair well with my CPU and GPU?
2. Will my huge Noctua nh-d15 cooler fit with my Corsair RAM? The reason i'm trying to buy LPX instead of RGB Pro is to have smaller size RAM to have enough space between the cooler and RAM.
3. Any suggestions for the amount of ssd/hdd (which one to use or to mix it)  and a power supply (amount of W)?
 
Thanks in advance!