You can first have age and gender question. Based on the response in these questions, you can have AgeAndGenderQuota that will have 2 (Male/Female) X 4 (4 age groups) X 3 (since you have 3 blocks) = 24 cells.
24 cells can be as below:
First 8 cells for Block 1
Similarly 8 + 8 cells for other two blocks. So, each cell will be given the limit that you want to set (in proportionate). Change the membership method to Least fill (percentage). Each respondent will qualify for 3 cells out of 24 cells but because of least fill, respondent will qualify for only one cell.
Now for asking the blocks, you can set a constructed list whose parent list will have 3 members (Block1,Block2,Block3)with the below logic:
1. If quota value = 1 to 8, then Block 1
2. If quota value = 9 to 16, then Block 2
3. If quota value = 17 to 24, then Block 3
Now click on the Randomized button and select Blocks. Select Add Set and then Add Block. Define 3 blocks with start and end anchors.
Select the Use Constructed List button and choose the constructed list you have created.
Similarly, you can set skip on Q32 based on value in quota question.
I hope this helps.