A translation from a later unit is taim se troithe ar airde - I am six feet tall. Is this exercise ising the wrong form of 'feet'?
Nice catch! We will correct this. Tróigh is one of nine words that have a special plural form used for counting with bunuimhreacha.
Yes. This exercise is using the singular form, which is the general case in Irish, but units of measurement should be expressed with the plural form (as the other exercise does).