I got a comment about the firmware version numbers. How can you tell which one is a newer and which one is older? Well ... Huawei really does make this one difficult. I'm guessing all this has to do with the fact that any regular user should be insulated from the fact that his/hers hardware is manufactured by Huawei. Your beloved telco should be their face and you should be doing business with them and only them. Screw that! 
This is 2014 and the age of social networking in the Internet. Openness is the only real way to go.
Here is what I gatehered for B593 u-12. This is a list of firwares from oldest to newest:
| Firmware name | HW ver | Release | Telco / Custom by | Version / Service Pack |
|---|---|---|---|---|
| V100R001C00SP052 | V100 | R001 | C00 | SP52 |
| V100R001C26SP054 | V100 | R001 | C26 | SP54 |
| V100R001C260SP055 | V100 | R001 | C260 | SP55 |
| V100R001C07SP061 | V100 | R001 | C07 | SP61 |
| V100R001C35SP061 | V100 | R001 | C35 | SP61 |
| V100R001C186SP065 | V100 | R001 | C186 | SP65 |
| V100R001C00SP070 | V100 | R001 | C00 | SP70 |
| V100R001C00SP073 | V100 | R001 | C00 | SP73 |
| V100R001C55SP102 | V100 | R001 | C55 | SP102 |
This is for B593 s-22:
| Firmware name | HW ver | Release | Build | Debug | Version / Service Pack | Telco / Custom by |
|---|---|---|---|---|---|---|
| V200R001B180D20SP00C1064 | V200 | R001 | B180 | D20 | SP00 | C1064 |
| V200R001B180D15SP00C00 | V200 | R001 | B180 | D15 | SP00 | C00 |
Just to be clear:
I don't know any of this to be factually correct, nor I can back any of this up from an "official" source. Feel free to correct me or suggest any other interpretation.
Update 18th May 2014:
Bilbo dropped me a comment with a link into https://app.box.com/s/0uim7fp7j4dzet2bpmhp. It provides more details about version numbering scheme Huawei uses. I did update the table headers with this new information.