Urine splashes on toilet seat

Q: I have had rectal problems for the past couple of years and I try to keep a slight gap at the back when I sit on the toilet. However, it felt like something fell on my back and I knew for sure it could not have been urine splashing on me. Later, I tried to check if urine splashes fell on me, but I couldn't tell. When I went the third time I saw one splash fall on the seat, so I was worried if this was happening all the time but I was unaware.

My questions are:

1. Do I have to have a shower and change anything that could have come in contact with me?

2. Are all of my prayers valid?

3. Have I made anything najis from touching that part of my body?

4. This is how most people use the toilet so should I tell my family members to be careful and sit all the way back.

Woman thinking of her father in-law

Q: If a woman thinks her husbands private part is her father in laws private parts or thinks they maybe similar to her father in laws private parts, and imagines her husband's private part and maybe also imagines the father in laws. Whilst having these thoughts (she hasnt actually seen them nor does she wish too) does thinking and imagining this affect the nikaah of the woman and her husband. She obviously knows her husband's private parts are his but she just got the thoughts explained above.

Calculating zakaat

Q: I wrote my gate exam. If I get qualified or get a rank then I will get a monthly stipend for my m.tech, around 12 500. Do I have to pay zakaat on that money?

If yes, then tell me the procedure. I mean is it compulsory on me to search for a needy person and give him or can I give it to anyone? Can it be added to an investment for the welfare of people/community by saving for public requirements in villages like for well, hospitals etc.?

Eating products with alcohol based flavours

Q: I recently contacted a company called Arnott's to find out whether one of their chocolate filling biscuit products, 'TimTam' was halaal and this was their response:

"Small amounts of alcohol based flavours (like vanilla essence) are added to sweet biscuits. We know alcohol is sensitive to heat and we believe the alcohol is evaporated during baking, but there is a slight possibility that trace amounts could still be present in the finished product."

Is this biscuit halaal?

Selling university textbooks

Q: A common business practice amongst university students is to buy and sell their used textbooks amongst each other (as buying brand new textbooks from the publisher is extremely expensive).

1. Students, along with selling their textbooks, sell the notes that they made and the lecture slides (pdf version) for that module (subject) as part of one 'package'. Our question is regarding the permissibility of selling the lecture slides - which the lecturer uploads online during the course of the semester - as some naive first year students are unaware that they will be getting them for free over the course of the semester.

2. A lot of textbooks come in an ebook (pdf) format which the publisher sells online (also expensive). It is possible to find a 'pirated' copy of the ebook on the internet and download it. Students also sell these as well at a cheaper price.

2.1 Is this permissible?

2.2 If permissible (2.1), will one get thawaab if one distributes it to students for free instead of selling it to them?