(edit title) Can you say this in swedish? Vad har du gjot/vad gjorde du, ikapp, vad/det Options

[chocolatecake2]

If you want to ask someone if he/she has caught up with his/hr schoolwork:
can you say:
''Är du ikapp?''
''Är/ligger du i fas?''

Another thing:

When do you use vad and when det in these type of sentences:

Har du läst vad/det jag har skrivit?
Det är säkre bättre än vad/det jag har skrivit.

Another thing I've been wondering about is that a lot of swedes say ''Vad har du gjort i helgen?'' if they ask about your weekend on a monday or tuesday or another day even though the weekend has already passed. Aren't you supposed to say ''vad gjorde du i helgen? and only say ''vad har du gjort i helgen'' when it's still the weekend(so on saturday or sunday) ?

Thanks in advance!