Participle phrase and the use of comma

English as a Second Language English Vocabulary, Grammar and Idioms
1
  1. What’s the difference between these phrases.

-The blog, which was hosted on servers located in the U.S, was removed and was sensored.

-The blog hosted on servers located in the U.S, was removed and was sensored.

-The blog, hosted on servers located in the U.S, was removed and sensored.

and

-Searches undertaken in June 2001 showed decreasing in petrol price, caused by uprising in the crude oil country producers.

-Searches, undertaken in June 2001, showed decreasing in petrol price, caused by uprisings in the crude oil country producers. (Does ‘caused by’ modify the entire clauses?)

Thanks

2

The blog which was hosted on some servers located in the U.S., was censored and removed.

The blog hosted on some servers located in the U.S., was censored and removed.

3

Don’t use the comma and the abbreviation mark.

Either
… in the US, was…
or
… in the U.S. was…