Quick questions about building new Z170 PC

Good Morning/Aftermoon/Evening,

I am currently building a new PC Skylake i7-6700K, I hadn't thought about how much I would to spend, but I don't want spend a lot in PC (forget the i7 think I think is very expensive) around 500€ without the CPU and GPU.

And I already did a lot of research but I have a few questions yet, that is the point of this thread, so first things first.

So I already have a few peripherals:
* Standard Keyboard;
* Standard Mouse;
* Standard VGA Monitor (I will upgrade later, maybe 4K);
* External DVD/CD Writer (I am thinking about put a Blu-Ray internal).

About the new specs for the PC:
CPU: i7-6700K 4,0GHz 8MB
RAM: Kingston HyperX Fury Black DDR4 16GB 2133MHz (2x8GB);
Case: I will build a custom one, but for now I will go with a "Zalman Z11 Neo" or "Zalman Z11 Plus HF1"
Storage: 1xSSD 128Gb (for System) & 1xHDD 1Tb (or similiar for games and normal storage)
MB: Not Sure
GPU: Not sure (SLI/Crossfire in future, maybe)
Power Supply: 650W ( +/- )

Well this is what I have for now

My questions are:
1) Motherboard, well I am still very confused about this one:
* Z170 for Skylake;
* I know that I will need at least 3 Sata Ports (1x SSD, 1x HDD & 1x Optical Drive);
* I would like to learn OC;
* I would want it to support SLI (I think all MB for Z170, for now, support SLI/Crossfire
- ASUS or MSI, and why? I know alot of information about the news Z170 is out yet
- After analysing the ASUS Ranger and Hero the only difference I see is about the number of SATA Ports where Ranger have 6 and Hero have 8, or there are other differences?
- The main difference between MSI Gamming M5 and M7
- Between the following MBs what you guys would choose, and why?
Asus Z170 Maximus VIII Ranger
Asus Z170 Maximus VIII Hero
Asus Z170 PRO GAMING
Asus Z170-A
MSI Z170A Gaming M5
MSI Z170A Gaming M7
MSI Z170A Gaming Pro
MSI Z170A Krait Gaming

2) Power Supply
* I would like to be 80+ Bronze or higher
- I will need to go with a modular one? Because in pcpartpicker always say "2 additional PCI-Express 6-pin power connectors are needed." when i go with SLI configuration, but if i pick a modular it don't gave me the error...

3) GPU, For now I will go with the onboard, maybe after 1 or 2 months I will buy one.

4) Other observations
- If you guys think I should change something feel free.

Thats it guys, I always search for the best ratio price/quality
Thanks and sorry for the long post,