Comma

Hello,

1. The book, which I found in the study, is about the quirrels of West Africa.

2. It would be lovely to have a long cold drink of delicious, freshly squeezed orange juice.

Is the usage of comma all right?

1. Contains a non-defining relative clause ("which I found in the study"), so the commas are necessary.
2. Because "freshly squeezed" is a compound adjective (where the left element further modifies the right element) it certainly helps the clarity and readability of the sentence to use a comma.

WARNING: There is a certain amount of disagreement amongst grammarians, about whether or not '-ly + past participle' is technically a compound adjective or not.  Depending on which book you read, you might get a different answer.