SAS baskets over SATA interface. How it works?

Question

SAS

Help me to understand.
Introduction:
We want to assemble a server on SAS 12G (just a dream), I chose screws and a controller, the only thing left is the basket. So far we have settled on Procase G2-104-SAS12-BK and SuperMicro M14TQC . However, I noticed that all the baskets that are sold are on SATA interfaces.
Moreover, if you take the sff-8482 cable, you can clearly see on it that where there is a jumper between data and power, there are also contacts. Likewise for screws.
Question:
1. What are these contacts for? If the basket is connected via a SATA cable, then where do they go?
2. If they are not needed, then why are they there?
3. Will there be a drop in performance if connected via a SATA basket? At the same time, a SAS-SATA-SAS scheme is drawn in my head, but again, where did the contacts go? (see item 1).
PS: You can, of course, throw the basket out of the chain, but what about cooling? I watched a video of a guy running SAS on a table, and after a couple of minutes the multimeter showed a temperature of 51 degrees, and as I understand from the specifications, 55 degrees is already critical.
PPS: check out the RAID build LSI 9361-4I + 4xST600MP0005 PPPS
: don't throw stones, first SAS build from scratch.

Answer 1

Found this variant of Procase G2-104-SAS12-BK:
This connector is SFF-8643 (mini SAS HD). Requires SFF-8643 (mini SAS HD)<->SFF-8087 (mini SAS) adapter.
Otherwise, in your question, the SAS controller is compatible with SATA drives/cradles, so the cables are almost identical. In your photos, it is apparently SAS / SATA baskets. Bandwidth limits must be specified in the specification of these baskets.
These pins are the second physical port on the disk, for example, to connect to a backup controller.

Answer 2

why do you need 12g if you still don’t pull so many disks.

Answer 3

We want to build a server on SAS 12G (just a dream)

Not that it is a direct answer to your question, but when I saw the mention of SAS12G, I could not pass by.
If you're interested in the subject of "racing server interfaces", check out a short post about SAS3 (12G) and SAS (3.0G) . There, on the old controller, we managed to get 790 MB / s .