Replying to the Salaam

Q: Is it obligatory on us to reply if anyone says to us Assalamu Alaikum Wa Rahmatullahi Wa Baraakatuhu? What will be the extent of that reply, do we have to say Wa Alaikum Assalam Wa Rahmatullahi Wa Baraakatuhu or we can just say Wa Alaikum Assalam? Whenever I receives your reply through email, there is always written Salaam in the beginning, do I have to reply to that Salaam as well?

Reciting Aayat-e-karima 125000 times

Q: I have started reciting Aayat-e-karima. Insha-Allah the intention is to complete 125000 times. I have two questions. 1) Since I have started the tazbeeh, can I continue in menses? 2) Can someone else also help me finish and complete the the tazbih. I have done most of the recitation but my cousin is helping me to complete only a few tazbeehs (8300) is that ok? Now only last 5000 are left.

Making verbal niyyah before salaah

Q: My question is related to making the verbal niyyah before salah. Is it a bida'h? I have gone through a lot of articles regarding this matter. Some people say that it is bida'h. Some say that it is okay to say it verbally whereas some say that it is not from the sunnah, that our prophet (Sallallahu Alayhi Wasallam) did not use to do this. He would rather make intention in the heart and start the salaah with Allah Akbar. I am confused with it and don't want to fall in doing something wrong. So if you can guide me to the right path Insha Allah. I also want to know if the intention is to be made in the heart only then what are things that should be said in the heart.