Passport stained from Water

[needinfo17]

My Passport is stained from water, the photo on the visa is stained but the information like First name ,last name,DOB,Visa expiration date etc are visible clearly.Already my visa is expired but have new approved 1-797 and 1-94.
But the Photo on the Passport is stained half.
My Questions are :

1) If I apply for New Passport, and If I go for visa next time and that passport wont have my visa, so will that effect me ?

2) At the time of visa do I need to carry both passports ?
3) With the new passport with me and old passport having stains is ok with the visa officer ?
4) Do I need to go to visa immediately once I receive the new passport ?

Please let me know with all these answers

Thanks for all your help