Update required.

[#1]

Looking at the pages relating to PN offers under the heading of Legal Bit, under the sub heading of pricing it says,
**PlusNet Value : If you Live in a Low cost area it costs £6.49 a month, if you live outside these areas it costs £6.49 a month .......
Assume this is a typo error ?

[#2]

"* Plusnet Value: If you live in a low cost area it costs £6.49 a month. If you live outside one of these areas it costs £6.49 a month for the first three months, then £10.79 or £12.99 a month depending on where you live. "
That's correct AFAIK.

[#3]

However if you follow What is a low cost area? there is no mention of the £10.79

[#4]

I see what you mean.

[#5]

Likewise there are only two prices for Plusnet Extra

[#6]

This has been covered at length
http://community.plus.net/forum/index.php/topic,98188.0.html
http://community.plus.net/forum/index.php/topic,97928.0.html
http://community.plus.net/forum/index.php/topic,97883.html
It is a limited time offer - how long for and whether once on it you stay on it is unknown