you can technically put all of what john said on the car plus:
-gauges, leave them unhooked just hook up the lights if u want
-fuel pump (though i would save this for just before the swap itself)
-exhaust and test pipe (car will be loud if u ditch cat)
-boost controllers/turbo timers
-relocating the battery if applicable
-you can even go as far as putting the front mount intercooler on or at least test fit it and have the holes done and bumper trimmed up and that will save time as well.

if i could do it over again i would definately have just did a normal buildup and done suspension and braking first, but i am in such need of power for so long now that i just skipped it all and went straight to go. which isnt bad but know that your brakes will at least be needing the asap upgrade as soon as you go turbo.

putting an 80mm (3.2") exhaust on an n/a car doesnt really lose power. i lost a little low end when i put my trust downpipe on, but all i got was alot of noise, lost my cat and such (and i have 2 piece header where i can do that). the low end loss everyone bitches about isnt noticeable at least to me it wasnt, its maybe 2hp? and the sound of some of the exhausts on a n/a ka is still a relatively good sound, some are noisy in high rpm (duh).

IMHO, i would get the swap first. then you can have months of cleaning it up, having it checked over by people to make sure its looking good condition, while you save up for the supporting elements.