a QCD is a direct reduction of your IRA distribution so nothing shows up in 4b (only 4a) and you don't get a charitable deduction. "QCD" should appear on 4b
if you have a tax basis in your IRAs the IRA distribution for the QCD will not reduce your tax basis. (won't show up on line 7 of form 8606) so if your entire IRA distributions were QCDs no 8606 will appear in your return.
rollovers would not show up on form 8606 but do show up on 4a but not 4b.
your 4a and 4b are correct.
