1. Definitely b. /var %var value can break in many cases (try //var %a 1, %b $str(c,%a) | echo -a %b and then //var %a = 3, %b = $str(c,%a) | echo -a %b). The proper (and documented) way is /var %var = value
2. This is again a matter of personal preference but in this case, $iif() looks like the natural choice. I could go on about suggesting in which cases $iif() would probably be a better choice than /if, but these are things that you figure out yourself as you gain more experience.
