Thoughts on replacing crankset

My suggestion would be take it to the LBS and have them look at it. Sometimes a cross-thread can be fixed and they might have the tools necessary. My next suggestion would be to find a used Dura Ace or Ultegra crank. Supposedly worth their weight in gold..

First thing I'd try is threading the pedal in backwards, to double check that the thread is actually stripped or cross threaded. Sometimes the lead thread can get damaged, preventing you from threading the pedal in, looks like a cross thread, but much easier to repair. Wait, I see you already tried that.
You could always heliciol or drill out and t-nut, but that's a lot of effort for the replacement cost (see below).

I was going to suggest getting a 105 crank, but looking over at chainreaction... they have gossamer megaExos for less than $60 - http://www.chainreactioncycles.com/Models.aspx?ModelID=10290
I think 105 is a better crank, but they are minimum $100 more.

Argh! Bonktown just had a 105 crankset...keep watching it, it will probably show up again today.

Another question, what is the difference between the FSA cranks that list ISIS drive others (the one I have does not indicate the drive type.  Also what types of measurements do i need if I would switch to a 105 or Ultegra?  

ISIS is a bottom bracket interface standard, the spindle is permanently attached to the bearings (more or less), sealed and separate from the crank. What you have is [FSA-speak] megaExo, on these, the BB spindle is permanently attached to one of the crank arms, the BB is just bearings that thread into the frame; FSA cranks come with the matching BB (better shops would mention this in the product description, but 95% of cranks these days work something like this).

If you got an ISIS crank, you would need a new BB, and IMO this would be a major downgrade - ISIS BBs are notorious for short life (it's impossible to spec a proper-sized bearning given the constraints involved, so they fail quickly).

FSA's megaExo and Shimano's BB standard (hollowtech 2) are interchangeable, so you can use a Shimano crank with FSA bearings. The only measurement you need are crank length and chainring sizes. MegaExo and hollowtech 2 are pretty clever in that you can't select the wrong BB for the crank, the bearings are all the same, and the spindle is part of the arm.

There are some tools you will need, that are specific to cranks and BBs. Assuming you don't have them (since you are asking the question), what a shop would charge to install might be less than the cost of the [rarely used] tools.

My LBS installed my Ultegra crank and BB for $10! The grease and Shimano BB tool would have cost way more than that.