Giving secular tuition and selling secular textbooks and notes

Q:

1. Is it correct to give tuition to students studying at secular universities? It would involve a male giving tuition to other males only.

2. Is it correct to sell the notes, past papers and textbooks etc. for certain subjects at secular universities?

3. Is it correct to sell the notes, past papers and textbooks etc. for certain subjects at secular correspondence universities (like Unisa)?

All three questions above relate to permissible subjects viz., mathematics, accounting and computer programming.

Husband drinking his wife's breast milk

Q: Suppose if a couple have a baby who has just reached 2 years of age and as a result baby's mother stops breastfeeding him. But there is milk left in the breast and the husband wants to drink this milk intentionally during foreplay. Can the husband do this because this milk has no use now as their child no more drinks breast milk. Please give me the answer as soon as possible.

Bride's family demanding a huge mahr

Q: I have one question regarding Mahr. The family of the bride wants to put 3 million BDT in the nikah contract which is totally unpractical and unreasonable. They are saying I don't have to pay any penny but they won't allow anything less in the contract. They might be asking this as a security in case a divorce takes place! How funny. Anyway, I would like to know the ruling on this. The bride has agreed to a much lesser amount which I can afford to pay. So if I sign the paper just to satisfy their parents and then I pay to the bride according to her wish will I be debt free? Will my marriage be valid?