No. Normal HDDs use 512-byte sectors. Only disks with Advanced Format like the new "EARS" WD drives use 4KiB sectors.
The higher the sector size, the more bandwidth/performance wasted when only updating a tiny bit in the sector; i.e. writing 2 bytes with 4KiB sector size means you actually read 4KiB then write 4KiB - total 8KiB of physical I/O for just writing 2 bytes.
1) No, The sector size is fixed by the drive microcode.
2) It depends. On balance, not a significant difference. On short(<4k) operations, perhaps a bit slower, on longer perhaps a bit faster.
3) A moot point if you can't pick.
The outer tracks of a hard drive are longer and contain more data per track than the inner tracks. Given a 7200rpm rotation rate, the outer tracks can transfer data at a higher rate, making them better performers.
4k sectors have larger overhead per sector, but there are fewer sectors per track, resulting in more useful data per track.