Can I retrofit a 5th line noseline to the kite?
the other questions are harder to answer.
The '09-'11 fuels have somewhat more depower ability on the bar than earlier fuels, but lack the split strut construction of both earlier and more recent fuels.
You still need edge and wind window control though, it is 100% C kite.
Split strut means the top of the strut is part of the top canopy surface instead of sewn onto it with a narrow tab of cloth as 90% of other kites are done. So each strut has 2 rows of stitching attaching it to the canopy, about 1.5" apart. It is claimed to help rigidity and durability, and give a slightly different feel. I think it actually mellows the kite out a little.
I would say all fuels from '09+ are good, relatively user friendly, and do not need fifth line except for a little extra safety.