My thought, esp for an urban PSK, is the 32tpi. 1) less "push" or "pull" required - teeth take smaller bites (slower cutting, but you don't have a frame or handle) 2) more useable for cutting thin metal - one usually wants to have at least 1 1/2 teeth "in" the cut 3) will still make fine cuts in small diameter wood, such as notches for a figure 4 trigger

It's not long enough to be significant for cutting firewood and even 18 tpi is slow compared to even a multi-tool or SAK knife.

As far as the type - bimetal are best, but a good quality carbon or tool steel might be a bit more useful in a PSK. Cost IS a reflection of blade quality in hacksaw and band saw blades.

You will need to abrasively "cut" a piece out of the blade - a bench grinder is simple or a cut-off wheel in an electric or pneumatic "die grinder" (Dremel tool). The edge of a whetstone will do, as will the edge of a concrete stoop (both slow). You can easily sharpen any portion of the blade as well - good steel with a good temper EXCEPT bimetal blades have "softer" bodies to resist breaking - hence my earlier suggestion that for a PSK a carbon or tool steel blade might be best.

Just my 2 cents worth

Tom