Mass storage total read/write and per interval read/write counters

/sys/block/sda/stat and the likes contains a list of very nice counters. They are user readable.

Field 3 and 7 are read/write counters in 512 byte sectors.

1. Would be nice to see them as $3*512 and $7*512 as total read and write counters, e.g. Total Read Bytes, Total Write Bytes
2. Would be nice to see the difference in measurements for each interval, e.g. Interval Read Bytes, Interval Write Bytes.
3. Would be nice to allow the user to select the unit, e.g. instead of showing bytes, allow to use kilo/mega/gigabytes (e.g. in 1000, 1 000 000, 1 000 000 000) but that will also require to allow to specify the precision.