[susan53]

3) Remember - if you use a preposition it must be paired with an "ordinary" relative pronoun (who, which, that). These may, as in your example sometimes be omitted but are still "understood". So :

We'll meet in the school (which) John graduated from last year.
That's the school (that) John studied in.
Tuesday? That's the day (which) my interview is on.


If you use "when" or "where", the concept of time or place is already included, so the preposition is irrelevant.

We'll meet in the school where John graduated.
That's the school where John studied.
Tuesday? That's the day when my interview is.


4. Either is possible - the word order is flexible here.