First Time Build LGA1150, Z97, i7 4790k/i5 4690k Please Help with MOBO+RAM

Hi, my 5 year old HP Pavilion Elite 9290f's MOBO (Pegatron IPMTB-TK) got bricked due to a CPU fan error. Likely, BIOS minimum CPU fan speed was set too low. I used to be able to press F2 to bypass but now it won't even allow me to pass anymore so I decided to build a new PC to upgrade the dated hardware (although a solution to this issue could be useful, I still am leaning more towards using as excuse to upgrade). The old hardware I want to transfer over to the new build is:
- Rosewill Armor Evo case with 6 fans (5x12" and 1x23")
- Coolermaster Hyper 212 EVO cooler
- ASUS GTX660-DC2O-2GD5 2GB OC
- Thermaltake TR2 600W PSU
- possibly some memory sticks I could carry over (the HP had 3x2GB and 3x1GB sticks DDR3-1066) though I am open to replace memory completely

My needs:
- Work (I'm a business student) but also a LOT for gaming on a single 1050p 60hz monitor most games maxed out more or less (aa can be downed). Not sure if finance programs like stock market clients are intensive and would benefit from hyperthreading.
- Z97 MOBO since apparently that will still be supported for at least one more cpu gen? Please NO X99, I don't think it's worth the investment for me with 2011-3 CPU and too new DDR4.
- Either i7 4790k or i5 4690k. WIth the only difference other than clocks being hyperthreading which correct me if I'm wrong only really helps with intensive stuff like rendering/mining not games this one is a toss up depending on how much I end up spending. My HP was an i7 920 rig so either one will be a nice upgrade. Please NO 5820k or other 2011-3, again not worth it for me.
- Min. 8GB DDR3 RAM (all new memory or re using some 2x2GB sticks+ rest new). Please NO DDR4, same reason as before.
- SLI support for future and OCing ability to push as much life as possible.
- Will get an SSD at some point so should I need M.2? Don't care for USB 3.1 since due to no chipset implementation revision MOBOs takes away from PCIe.
- Enough fan headers for most if not all 6+1(cpu) fans.
- Looks don't matter, also note for pricing I'm in Canada.

I have narrowed down to these 2 boards:

$160 Asus Z97-A (M.2, 2 less headers than fans, only hispeed memory optimization button)
https://ca.pcpartpicker.com/part/asus-motherboard-z97a
$180 Gigabyte GA-Z97X-SOC (no M.2, enough fan headers for all fans, bunch of oc buttons)
https://ca.pcpartpicker.com/part/gigabyte-motherboard-gaz97xsoc

Didn't like the MSI offerings and as much as Asrock is getting better still don't trust them.

MEMORY
What would be my best options for memory? Good sticks but not too expensive. Heres a list of the ones I've narrowed down by specs/price ratio:

2x8GB
$135 Crucial Ballistix Sport DDR3-1600 CAS 9 1.5V
https://ca.pcpartpicker.com/part/crucial-memory-bls2kit8g3d1609ds1s00
$145 G.Skill Sniper Series DDR3-1866 CAS 9 1.5V
https://ca.pcpartpicker.com/part/gskill-memory-f31866c9d16gsr
$145 G.Skill Sniper Series DDR3-2133 CAS 10 1.6V
https://ca.pcpartpicker.com/part/gskill-memory-f32133c10d16gsr
$145 G.Skill Sniper Series DDR3-2400 CAS 11 1.65V
https://ca.pcpartpicker.com/part/gskill-memory-f32400c11d16gsr

2x4GB
$71 G.Skill Ripjaws X Series DDR3-1600 CAS 7 1.5V
https://ca.pcpartpicker.com/part/gskill-memory-f312800cl7d8gbxm
$85 G.Skill Ripjaws X Series DDR3-1866 CAS 8 1.5V
https://ca.pcpartpicker.com/part/gskill-memory-f314900cl8d8gbxm
$85 G.Skill Ripjaws X Series DDR3-2133 CAS 9 1.6V
https://ca.pcpartpicker.com/part/gskill-memory-f32133c9d8gxl
$85 G.Skill Ripjaws Z Series DDR3-2400 CAS 10 1.65V
https://ca.pcpartpicker.com/part/gskill-memory-f32400c10d8gzh

1) Is there even a need to upgrade, can my described issue with the old mobo be solved?

2) Given my needs is this a good build or overkill?

3) Feel free to suggest other MOBOs and RAM but also please recommend which of these to get.

4) Are the DIMMS I've linked a good price or a bit high? I tried to sample all DIMM speeds and tried to keep down latency.

5) What's the real world difference in performance across DIMM speeds and latencies?

6) Does lower voltage RAM mean more OC potential (crazy expensive DIMMS seemed to have higher voltage)?

7) I heard anything above DDR3-1866 is unnecessary for gaming unless it's a same price DIMM, do you agree?

8) I might also need an extra hdd at least 1tb, would appreciate a recommendation for a good not too expensive hdd..

Thanks for the help and sorry for the wall of text, wanted to be detailed.