1.This link is only the shaft and switches for mechanical keyboard,no keyboard included.It's 5 pin switches
2.It can support SMD leds.
If you want to install 2 pin 4 pin switch leds, you need to solder led at first onto PCB and then put on switches on
3.TTC Ace is linear switches,actuation weight is around 53gf.Bottom out weight is 60gf.Conduction stroke is 2mm,total travel is around 40mm
4.The lifetime is around 100 million times