How would you say "We GO (usually) to school" then ? Is there another present tense I am not yet aware of ?
It would be 'my chodzimy do szkoły'. 'Idziemy' refers to the present and 'chodzimy' in this sense refers to regular activity. Both are in a present tense but in a different aspect.
For the first time I saw a black box above the lesson telling me that my translation "I walk to school" was wrong and explaining the difference between Idziemy and Chodzimy. That's amazing, I'm very impressed with how useful that sort of thing will be. Usually I have to go to the forums to find out things like that!
Chodzić and Iść are actually the same aspect, imperfective. In Polish, the imperfective is used to express both habitual action, and continuous action. So usually you would use the same verb to say both things, but these two verbs seem to be a bit of an exception.
my idziemy= we are going/walking (right now) (with a destination)
my chodzimy= we go/walk (usually)
my chodzimy= we are walking (right now)(without destination)
I once went through all the sentences in the Verbs of Motion skill and deleted the translations that do not follow those rules, so if you find anything that doesn't match it, please comment there.
So, how does one say "We walk to school?" Chodzimy do szkoly? - or is that too frequentative? A mushy translation task.
Why is it in the genitive case? Is it just a thing that the preposition "do" does?
As a native English speaker, I think "We are going to school" definitely means that we habitually attend school. To make it mean "we are presently walking," a determiner is needed, like "to the school" or "to our school."