The one posted in that picture was the regular SSA, not the SSA-E. However, it depends on how you like your triggers. The SSA is 4.5lbs and the SSA-E is 3.5lbs. The SSA and SD-C are the same, as are the SSA-E and SD-E the same. Keep in mind that the weight of a 2-stage trigger has a tendency to feel lighter than a single stage of the same weight.
If you aren't familiar with their application guide, take a look at it:
The prices on them are pretty constant across the board regardless of where you go. The only way to get discounted pricing is to have LE/MIL discounts with vendors. Buying a whole LPK with a Geissele instead of the milspec trigger is a way to shave off a few bucks.
I personally prefer my Noveske 60 degree safety, but Battle Arms Development is a top notch company with a very excellent reputation and I would not hesitate to buy their products.
There is a third pin included in the Geissele trigger kit, but it's not an operational pin. It's a rounded off slave pin that just assists you in installation.
Or what lever are you referring to?
The lifespan is basically an average life of the trigger before it will mechanically fail. The main part that fails on the two-stage is that club foot tail that comes off the back of the hammer and engages the two trigger disconnectors attached to the lower trigger portion.
RRA is known to have the worst reliability of all 2-stages, and you can see this by the very long and narrow shaft of that club foot tail. In contrast, you can see that the KAC is beefed up and is shorter, and the Geissele is the shortest and most beefed-up of all. RRA triggers are known to fail very early and with low round count. They're not combat-capable triggers, which is why they're billed as a National Match trigger.
I don't know what KAC's life span is, but when you consider that the KAC 2-stage costs $329 and the equivalent Geissele SSA costs $210, it's sort of a no-brainer.
As has been stated, Geisseles are rediculously reliable, and there's a reason why they have a lot of SOCOM contracts.