Because hotlapping is "ajo kelloa vastaan", i.e. racing only against the clock. Aika-ajo means qualifying, i.e. determining the starting order of the race.
IMO.
Yes, there is a file to change it, [LFS dir]\data\language\Suomi.txt 13th, 14th and 808th row.
My point is, partly since Finnish is extremely rich in homonyms, to try and simplify the translation even though it might not literally correspond with the English equivalent.
Plus, though this is only me saying, it would be beneficial if the translation actually sounded like Finnish.