I'm not sure which contradiction you are pointing at. David Vielmetter just tells the disk is NTFS formatted, and Anandtech tells something about sector sizes. That is no contradiction.
It is not really important what the internal sector size is. No matter what it is, the logical sector size is 512 bytes. The only problem the internal sector size can give, is partition misalignment, which can have serious impact on transfer speed.
The 4k sector size behind the usb bridge is a problem. This is a trick applied by most (all?) sata-usb bridges for disks larger than 2TB, indeed for XP compatibility. The 'classic' MBR partition table can store an 32 bit start- and endsector for the partitions. So the biggest endsector is 2^32, which is about 4000000000. If you multiply that with the 512 bytes sector size, you get 2TB.
XP doesn't support another partition table format, but it happened to support 4k sectors. Using the same partition table, the max partition size is suddenly 8 times as big, up to 16TB. Everybody happy.
The problem is that the disk was connected to a sata bus, which shows 512 byte sectors. (The disk has a GPT partition table to be able to handle 3TB). The partition start and end are given in sectors, so if suddenly the sector size changes, the partition is not where it ought to be. That problem could be solved by generating a new partition table, but possibily the filesystem internally also uses sector numbers.
So a disk partitioned and formatted on 512 bytes, has to be read on 512 bytes. An usb-sata bridge is not usable.
I tried inserting a sata cable, albeit with a little force but the drive wouldn't get detected
Did you also power the disk? A sata cable doesn't provide power.
a) Undetectable drive. What is the best option to get my laptop to recognise it?
If the disk is correctly powered and connected to an (e-)sata port, and yet not recognized, then it's dead. Only a data recovery business can possibly recover it. (BTW, 'not recognized' means here that your laptop doesn't detect the disk at all. A raw disk is recognized)