Things which render the Salaah Makrooh

Q: I am a chain smoker and after every namaaz I smoke, what should I do to offer next namaaz? Do I need to make wuzu again or the wuzu from the previous namaaz is enough?

Also, is smoking haraam or makrooh?

Q: I am taking a class that goes from 5:30 pm to 8:30 pm. Hence it covers asr and maghrib prayers. The class is located far away from where I live. In order to maintain purity (wudhu) for both prayers (there is no cleaning facility at the class location) I used to hold myself not to urine during the entire 3 hour session. Hence for both prayers, especially for the maghrib prayer, I am exerting a huge effort not to let anything come out during the prayer (3 hours are very long). Is my prayer valid?

In addition, even though I tried my best, I cannot guarantee that my pants is 100% clean when I start praying as it is possible that some urine come out while I was in the classroom (that is outside the prayer, before it starts). Does this possible impurity affect my prayer? I almost did my best but I really don't know if my prayers are valid.

Q: Is it permissible to pray salat wearing a t-shirt which contain a picture of human which is kept coverd?

Q: Is it permissible to offer prayer while wearing a bag?

Q: Regarding it being impermissible to perform Salah when there is a need, does this mean if it is extremely urgent, or a slight feeling that one has throughout salah.

For instance, feeling gassy after eating certain types of food etc. Because I am constantly breaking salah when I get a feeling to use the toilet to pass wind.

Q: I read salah in front of a glass and my reflection was on the glass in front of me, is it permissible? 

Q: Is it ok to perform salah in a room that has pictures of cartoon/Barbie's or with the kids toys having clear faces on it? Kindly enlight me 

Q: Is it permissible that a person can offer Salah in a t-shirt that is half sleeved and does not have any image printed upon it? Also what is the ruling regarding three quarter shorts.

Q: What are the consequences if one prays Namaz with their clothes covering below the ankles ?

Q: My son shaves his face fully due to his job, so does his prayers get invalid.