Joining two Salaahs

Q: I have heard one is able to join prayer like zuhr and asr when need be. I am a student and I can never get any work done at home so I go to the library. Only the time between the two namazes are like three hours. Is it ok for me to join the two in this case because that gives me so much more time to sit there and get my work done?

Performing Tawbah Salaah

Q: How do you make the niyyat and pray the prayer of repentance. I have heard you make wudhu and pray two nafil. But what do you say in the niyyat exactly and is there anything special you say after the namaaz? Also can you make wudu for Esha namaaz, pray the repentance namaaz and then pray isha right after with the same wudhu?

Making tawbah from zina

Q: I did a terrible terrible thing. I cheated on my husband. I slept with a whatsapp contact of mine twice. I know I did wrong and I am so sorry for what I did, I mean it was a total stranger. My husband is taking this very hard and I know he still loves me and I am thankful for that. What can I do to revive our marriage and make my husband look at me the way he used to before he found out. Will things ever be the same again?