CPU mining is a thing of a past and even if people who indulge in CPU mining in this time have modern and powerful CPUs (Ryzen, Xenon, etc.) to make it any profitable.
Anyway, can you mention the proper model number for the motherboard you have and the CPU model for the first one?
It'll help to better assist you.

I have quite of few of them and each of it consumes 80-85W mining ETH only at 24-25 MH/s.
A rig of six cards as such with other things considered will consume around 600-650 W from the wall. So, I guess that's fine.

The latest drivers will do just fine. (Don't forget to DDU and set virtual memory to 20GB+, also try RX boost for a little more hashrate.)
Instead of using afterburner, try overdriverNtool - use it to find sweet settings spot for clock speeds and voltages.
If you want to push them a little more, use memory tweaker to tweak memory timings.

It's just a cloud mining contract in disguise.
Anyone who is even slightly involved with mining will know that this is all just a diddle.

It's about time they plan and implement features regarding privacy in their blockchain ecosystem.
I like privacy coins but they are mostly marketed on the basis of privacy only and not many other functionalities.
A mixer is a good addition as it won't require hard changes to be made and can be easily implemented.

DDU and install the latest drivers, add an exclusion for the folder Claymore in Windows Defender and try to execute the miner using CMD (Run as Administrator), cd in the Claymore folder and execute it with correct parameters as in the bat file.

Well, L3 has N factor hard-coded. (Scrypt-N) N factor is a value which increases the memory requirement to compute the hash for the same algorithm which renders the ASIC with less than required N factor obsolete.
It is similar to DAG implementation for Eth hash based coins like Ethereum where the memory requirement for mining it will increase over time, thus producing ASICs for them quite a challenge.

No, L3 chips (ASIC) are hardcoded to compute only Scrypt hash functions.
It cannot compute nScrypt.

No, there is not. The script automatically pulls the latest version of the miner to be copied into your VMs. Now for the configs, keep it default as the post because they are extensively tested and in working. If you tinker with the configs on your own without any technical knowledge of the same, it may cause problems and it will be a nightmare to solve it.

No, the above is the main component for this to work. You cannot evade the 4% fees. Moreover, why is it a problem to provide 4% when you are using someone else services or methods?
NOTE: 2% is for the method/ script creator and 2% for the authors of the miner. (xmr-stack)

What have you tried up until now to get it working?
Anyway, download an old version of the miner as gridseed orbs are pretty old and outdated and probably BFGminer won't detect them properly. (try cgminer version 3.7.2)

NOTE: If you haven't flashed custom bios up until now, back up your original one before proceeding further.
1. Reset everything --> Flash original bios and then find a custom bios which can OC higher for your RX590 according to the memory vendor of the card (Google for VGA bios).
2. OC mem clock in intervals of  +50MHz and keep doing it until failure.
3. Downclock core clock in intervals of -25MHz and keep doing it until the hashrate is affected.
4. Down volt Memory and core respectively again till failure.

User OverDriveNtool and save your configuration once you figured out the best settings possible.

If you are concerned with using a virtual machine or a fully-fledged program over the Windows 10 that I'll recommend you to check these out:
Phoneix OS
Bliss ROM
The above two are a separate OS that you can dual boot with Windows and run your Android apps without any lag or issues. Just check for compatibility before-hand.

Do you have a small single board computer like Raspberry Pi or Orange Pi2+ or any other variant? Then you can use CLI interface of Solaris wallet over a CLI Linux OS with no memory problem at all.
I've been doing this for quite some time now and it's been two months of continuous POS mining without any issues and rock solid stability.
If you usually go for POS coins and it's respective mining then the above hardware might be a good investment as it will cost in a range of $20-$30.

I have mined some coins in the testnet period and now when I'm syncing my wallet and imported my private key, half of the coin amount is showing under locked status. Why is that?
Anyone have a link where you can download blockchain to a certain height so that the sync process happens faster?

EDIT: Read a few pages, found out that devs provided 2x amount of the coin mined under testnet and by the looks of it, I don't think this project is going anywhere.
EDIT2: If anyone is looking for download links to GUI wallet, nodecore and bootstrap. Here it is: https://explore.veriblock.org/api/stats/download

What is your power consumption for the GPU alone?

Check the memory vendor of your card through GPU-z software.
If it is Samsung, the memory will easily overlock to +800 MHz. For Micron: +500 seems achievable and Hynix then you're out of luck as it sucks for overclocking memory vector.
As Ethash algorithm highly favours faster memory speeds, it is crucial to overclock memory parameter to achieve highest hashrate possible from the cards.

If it's still under warranty, I'll recommend RMA'ing it.

Create two bat files, one for RX580 and the other for Vega and then run them simultaneously.
In the first bat file mention -g 0 and in the other mention -g 1.
It should do the trick.
BTW, Don't forget to check if you have virtual memory set to 16GB.

I started selling most of my cards a few months back.
Still left with few which are down as of now.
Anyway, I definitely believe that even if the price corrects itself to some good levels like $400-500 for ETH which can take some time, there will always be GPU miners that will turn it on proportionally to the profit that they will be making after electricity cost. (A linear than exponential.)

It will all depend on which mineable coin becomes more profitable in the future. It can be a totally new coin with a different algorithm that we don't know about or it can be something that already exists.
Still, Nvidia GPUs are an all-rounder and they perform really good at hashing many different algorithms and okay in the rest whereas AMD GPUs are beast at what they are compatible with.
Anyway, I'll recommend going for RTX 2080.