Not to be rude or anything but, in my opinion, walnut works great for both fretboards and bodies. I have built two strats out of walnut and they sounded great and were slightly heavier than a strat (my prefrance compared to a rip your arm off from weight les paul) about the expansion and contraction, I live in northern Minnesota where the humidity and temp. are never the same one day to the next it can be 70 degrees in the summer with high humidity then the next day have very low humidity and in the winter it ranges from -40 to 30 degrees farenheight with very low humidity so it's is hard to keep wood in the same range (esspecially seeing as I use three different shops in my area) but besides all that I have never seen a guitar where the frets came loose on a walnut fretboard. I got the idea to use the wood as a fretboard from Kevin Skaja (Skaja Guitars) who builds acoustics with walnut fretboards and I have never seen one of his guitars frets come loose over seasons. I'm not saying you are wrong I'm just going with my personal experience on this one. And yes walnut does make beautiful tops especially with maple binding.
Yeah the tamarack I have is pretty freaking hard, I looked up and compared it with maple and white ash (the book was printed talking about trees native to Minnesota so I know what to expect out of native woods instead of say maple from some other state, there are differences) and they were almost identicle and I want to try using it, I have thought about the fact that it would be kind of hard to replace it, unless I took the guitar to a band or table saw to cut the center out.
I might just end up using it for the body wings though like I said before I haven't fully decided what wood goes where yet.
The reason I chose these frets is I have never seen them on anything and I am curious as to if they are any good, and seeing as I am keeping this guitar and not selling it I thought it would be the best one to try them out on. I do bend by hand (no point in buying a modified can opener for $90 when I can do it myself) but I don't just hammer or press them in, I fill the slot with super glue then "slide" my hammer across the fret with even pressure and then squeeze clamp a radius block equal to the FB radius to it and let the glue dry. Doing this I have only had to level one fretboard (my first neck) and yes i do check the frets with a straight edge when I'm done to double check it.
Thanks and I'm using Seymour Duncan Full Shred humbuckers http://www.musiciansfriend.com/navigation?q=full+shred