Mark Knopfler Stratocaster®...
Although I am not a guitar expert at all, I can tell you some things about it..
It is a Fender Stratocaster, which came on the market in 1954 and pretty much all great guitarist have used one (Eric Clapton, Stevie Ray Vaughan, Kurt Cobain, Jimi Hendrix, Bryan May... and of course Mark Knopfler)
Mark even has his own signature stratocaster! So of course, the photograph you took shows one of them... His signature stands on the top of the guitar.. You clearly see it on this picture:
The Mark Knopfler Stratocaster guitar is a true “Sultan of Swing,” with a Hot Rod Red ’57 Stratocaster ash body and vintage tinted ’62 C-shaped maple neck with rosewood fingerboard. Knopfler’s unmistakable tone comes from three Texas Special™ single-coil pickups and a five-way switch. Other features include Fender/Gotoh® vintage tuners, an American Vintage tremolo system, and Mark's signature on the headstock!
It is worth lots! And actually, because of the economy (partly), it is cheaper in America. I think it's about $2200, however there are always discounts in shops..
The best amplifier to use -- well, opinions differ -- is a Marschall amp.. Brilliant sound!
And the songs that Mark plays on it... Well, Sultans of Swing for starters, Postcard from Paraguay... Lots, and too much to sum up 
When it was guy Fletcher's birthday, Mark gave this guitar to him at the end of the show!
Hope you had something about this reply, any questions, do ask..
"The birds up on the wires and the telegraph poles
They can always fly away from this rain and this cold
You can hear them singing out their telegraph code
All the way down the telegraph road"
"My darling boy, all of my sunshine and all of my joy"