Solution:

They were facing each other and not back to back.

Solution:

Not sure.

John Brunner always sneezes before the rain, but it was not mentioned that if Brunner sneezes, it will rain.

Solution:

On Your lap.

Solution:

Treasure Map Is Hidden Inside The Hanging Room Floor.

Explanation.
Just reverse the text "roolF mooR gnignaH ehT edisnI neddiH sI paM erusaerT".

Solution:

TIF56

Explanation:
The password is formed as:
T (5th letter of Shruti)
I (5th letter of Arshika)
F(1st letter of Friday)
5(5th day of week)
6(Length of Friday)

Similarly, we will pick the 1st letter for Monday and 3rd letter for Wednesday.

Solution:

1000$ - (Profit he earned in antique watch)

Solution:

Congratulations

Explanation:
Message Was: Company Piano Numb Dining Racial Mozetta Traitor Meou Legacy Quintana Trick Missi Orange Frozen Sapphire

Pick the 1st letter of the first word, 2nd letter of the second word, Pick 1st letter from the third word and so on.

Company - C
Piano - O
Numb - N
Dining - G
Racial - R
Mozetta - A
Traitor - T
Meou - U
Legacy - L
Quintana - A
Trick - T
Missi - I
Orange - O
Frozen - N
Sapphire - S

Solution:

They were playing tennis.

Tiger Phil
30 - 30
40 - 30 (Phil hit a bad shot)
Game won - 30 (Tiger hit an awesome shot)

Solution:

Are you Thorgan

Explanation:
Below will be the reply of three brothers:
Eden: No (speaks truth)
Thorgan: No (speaks lie)
Kylian: Yes (speaks lie)

Therefore if its Kylian then only you will get a reply as "Yes" and then you ask for your money.

Solution:

In Mansion M2, we know that older child is boy, therefore there are two cases
Older Younger
Boy Girl
Boy Boy
Probability of at least one girl child: 1/2 => 50%

In Mansion M1 there are three cases
Older Younger
Boy Girl
Boy Boy
Girl Boy
Probability of at least one girl child: 2/3 => 66.67%