Being eligible for zakaat

Q: I am zakaat liable and collect zakaat from time to time from people, however this month I collected a large sum. Can I take out money for my kids Madrasah fees, transport fees and whatever I wish to pay for in the future and keep it aside so on a monthly basis I will have enough to pay for my expenses?

Example, I take out R1200 and keep it aside for fees from April till July so when I get my salary I can use that for other things I require.

Will I still be able to collect zakaat after this?

Irregular discharge

Q: I had a problem of irregular discharge. I used to experience yellow discharge almost every day. Depending on my previous habit, I used to count my tuhr days as 23 and my period days as 8. Last month, after my period ended on 29 January. I experienced discolored discharge on 30 and 31st January. Then I was totally clean for 15 days. After that I started bleeding on 15 February. I counted it as my period. And it ended on the 10th day on 25th February.

1. Was it correct for me to count my period from 15 February?

2. What will be my new tuhr habit and period habit?

Accountant taking out a portion of his wealth and giving it to the poor for recording interest transactions

Q: If I work in an accounting environment where interest and insurance etc. will be recorded and calculated, will the tax I pay on my salary be enough to purify my income or should I take out a certain percentage every month as a way of purifying my wealth from Haraam and doubtful?