The BB hight feels fine, I have not really ridden the frame that much whit 26" so comparison is hard - but it handles really well, the forks are 100mm and that work good, but i think that 120-140mm will make it unstable.
That looks pretty good. My BFe has loads of clearance so I'm sure that it'd take bigger wheels easily. There's not a huge amount of difference between a 650b wheel and a 26er so I doubt the affect on the geometry is too great.
A chap who sometimes rides with us has the Solaris and throws it around pretty easily and is super quick on it.
I have ordered the some parts to finish the build, CK headset (really dont like the bbb), a bashgaurd from BBG and a 32t truative chainring. cant whate to have it ready for some real action..