T570: M2 NVMe + additional 2,5" SATAIII?

[hirnsaege]

So i'm considering to buy a Thinkpad T570 ... (or a T470 or P51s), highend configurations (NVMe SSD and hiDPI screen).

From what i get from reviews (correct me if I'm wrong):
– this has an NVMe SSD installed, that has the 2280 form factor and sits in an adapter of the 2,5" drive bay and is connected via PCIe with two lanes.
– In this bay, i could also put in a 2,5" drive there (that is SATAIII only then due to drives limitations).
– there is an additional M.2 slot, where i could add another SSD, but only with small form factor 2242. I am not sure if there are PCIe lanes attached to this, or if this slot is SATAIII only (mixed information).

From my old notebook i still have a Samsung 850 Evo 1TB. If possible, i'd like to re-use the Evo drive as a second drive.

Questions are:
– I guess adding the old 2,5" SSD is not possible without dropping the original drive completely as this does not fit in the second M.2 slot? (this is no option of course)
– If i added a *new* second drive to the M.2 slot, would that always be connected with SATAIII only, so be limited to 500MB/sec, or is there more to achieve?
– are there any differences in this regards between T470, T570, P51s (or T470p, which is a remote option).

thanks for your help
Tom