cheese cream or cheese and cream or cream and cheese
No, you can use any brand of cream cheese you have.
you use cream cheese not regular cheese
Cream Cheese
You can add milk to cream cheese so it isn’t as think, then use it as substitute for sour cream
No. That would be disgusting.
Yes you can
If you use less cream cheese than the recipe calls for, there will be less cream cheese in the prepared dish. Depending on the other ingredients, the effect may or may not be noticeable. I would suggest using the amount of cream cheese that the recipe calls for. You might be able to use a portion of plain (unflavored) yogurt in addition to the lesser amount of cream cheese to save on calories or fat content, but I would still go with the full amount of cream cheese that the recipe calls for.
Milk
I wouldn't, no.
cream cheese
A basic substitution would be to use cream cheese instead. If you have a little time, a mixture of 1 tablespoon of cream mixed with every 8 ounces of softened cream cheese is better. If you don't have cream handy, you can use butter to blend with the cream cheese instead. Or use 1/4 cup of whipped cream.