Cleaning thoroughly in istinja

Q: I passed stool and made istinja and I checked with tissue there was no impurity then i did wudhu and I felt there is some impurity but I did not clean it as I was not sure about it. I offered namaz in this condition and after namaaz I checked so there was impurity. Then I cleaned it off and I did wudhu and offered namaaz again. Now I am very worried that as I had offered naamaz with impurity so my Imaan lasts or not? Do I have to do ghusal? I recited Kalima shareef and made tauba but still I am so worried. Please guide.

Verification of a Hadith

Q: Is this authentic, please give reference?

One day Rasulullah ﷺ asked Jibreal عليه السلام, "Have you ever travelled at full speed?" Jibreal عليه السلام said, "Yes, on four occasions." Rasulullah ﷺ asked, "What were the four occasions?" Jibreal عليه السلام said, "First time was when Ibrāheem عليه السلام was placed in Nimrud's fire. At the time I was near the Arsh-Throne. Allāh ordered me to cool the fire. I left the Arsh and descended seven heavens in time. 

Second time was when Ibrāheem عليه السلام was about to sacrifice his son Ishmael عليه السلام in Mina. Allāh ordered me to replace his son with a lamb, before Ibrāheem عليه السلام struck with his knife.

Third time was when, the brothers of Yusuf عليه السلام threw him into the well. Allāh ordered me to save Yusuf عليه السلام, I rushed and placed my wing underneath Yusuf عليه السلام before he reached the bottom of the well.

And the final time was when you, Ya Rasulallah ﷺ, injured your tooth at the battle of Uhud. Allāh Ta'ala ordered me to stop your blood reaching the ground, otherwise no plant or tree would grow, till the end of the world. Hearing this, I rushed and saved your blood with my wings."

Ghusal for a man who inserts his private part into another man

Q: 

1. When a man inserts his tip of penis in other man's anus, both should have fard ghusl right?

2. Is the ghusl fard even if when both had worn clothes? E.g. If one had worn pants and the other had also worn pants but the penis went inside the anus along with both pants. Is ghusl still fard?

3. Is the fard ghusl same as ghusl janabah?

Oral sex

Q: If a person is married and they engage in oral sex and the fluid goes in either of the spouses mouth and they swallow it does this have the same ruling like eating something haram?