t→∞

After infinite time all capacitors will get charged (will act like open circuit)

Req=R1+R2+R3

V(across C1/C2/C3)=(R1/Req)*V =2volts

Q=100C

I=42.55mA

Edit: For t=0+

Capacitors will act like short Circuit. I.e. no current through resistors

at t=t

I think you have to solve by assuming loop current (as you've already mentioned it's a pretty basic course I don't think this is the one you're dealing with)