b) does CPU mining still work at 8192 and beyond?
Benchmark and test run at N=32768 I ran and posted on the previous page to dispute TacoTime's claim hash rates will drop to double digits in a year:
Platform: IBM HS21 blade server, 2x Xeon E5450's (similar combined performance to one i7-2600k).
For N=32 (at coin's launch), hash rate = 358.77 kH/sec
For N=256 (right now), hash rate = 119.25 kH/sec
For N=32768 (in one year), hash rate = 0.606 kH/sec
(if not, then we have a problem on our hand that would at minimum necessitate a hard fork I'd think).
If the scrypt-jane library starts having trouble at certain values of N (and it looks fine up through at least N=32768 that I've tested so far), I'd think we would only need to fix the problem in the library and release a new update to the client, rather than hard fork.