Hadith verification

Q: I just wanted to know the actual hadith and the reference. They were both in regards to the ummah being forgiven.

1st Hadith more or less - our Beloved Master Sallallahu Alaihi Wasallam was travelling and near the outskirts of Madina made dua 3 times and fell into sujood 3 times - was informed each time 1/3 of the ummah was forgiven each time.

2nd Hadith, the Beloved Sallallahu Alaihi Wasallam was told He would be very pleased with how Allah Ta'ala will treat the ummah on that day.

Replying to salaam correctly

Q: A known person to me sometimes greet me as Assamualekum without la in it, clearly. Sometimes I reply to him in forgetfulness Walekum assalam, instead of Walekum. Then I realize that, and don't know what to read as a counteract to that. Could you please tell me what to do at that times?

Fasting while travelling

Q:

1. I have read that one can only miss his fast if one is a traveller at sehri time. What will be the ruling of an individual who is travelling abroad but his  light is at afternoon time (meaning he is still at home at sehri time)?

2. If that person needs to fast, how will he do Iftar because different countries have different iftar times.

3. Also, will putting Vicks under the nose and sniffing it throurg out the day break one's fast? I have read that it doesn't because it does not have a body. Will that have the same ruling if one was to sniff Vicks from a tissue (i.e. putting some vicks on a tissue and then inhaling the subtance form the tissue?