First DVI-I is dual link digital and analog supported. and should be capatible with all monitors made in the last 2 years or so.
Correct. If you have a HDMI 1.3a cable it will support anything that specifies any version older than itself. So a 1.3a cable (90% of the ones on the market) will work in a 1.2, 1.1, etc. device no problem. The only change was was improves in how the signals get transferred which resulted in higher bandwidth, higher throughput. The actual plug has never been changed and never will be changed. They added a clause in the standard to not change the plug except for the rules about HDMI mini port, but no product I know of has used that yet. See link below.
http://en.wikipedia.org/wiki/HDMI#Versions
DVI can support up to 2560 x 1600, but the higher the resolution, the lower the maximum refresh rate. At say 1280 x 1024, both DVI and HDMI will refresh at up to 75 hz, but at 1960 x 1080 (i think that is right) DVI will be limited to 60 hz and lower, while HDMI will still be capable of better.
Hell they may TV's now with 120 hz refresh rates on HDMI.
DVI dual and single link doesn't effect bandwidth. A DVI dual link will support both analog and digital signals (DVI-I). A single link (DVI-D) will only support digital signals. There is a whole bunch of other variation and rules about linking which kind of DVI cable to what, but honestly a PC monitor only needs one link that is digital, yet most GPU's have DVI-I links on them for people who still use there VGA only monitors.
There was a plan to use the second link in DVI-I to carry a audio signal, but I think it was abandoned when DisplayPort's specs were finalized. If they are still working on it, basically the video will be on the digital link on the DVI-I and the audio will be transmitted as a second analog signal on the link that is normally for a VGA signal.