My Pastor does not allow us to celebrate Christmas during Advent, tells us not to decorate our homes and forbids any parties on Church grounds until December 25. Is this right?

The liturgical environment has stricter rules than Catholics are necessarily obliged to follow in their own homes. While it may be ideal that our homes perfectly reflect the liturgical cycle, practically speaking, many Catholics begin decorating earlier in the month of December.
 
As for celebrations on Church grounds, that is a matter of pastoral judgment. Frankly, most pastors are rather relaxed about this, understanding that cultural influences, even if less than ideal, can be respected out of regard for the legitimate wishes of people to celebrate conveniently.
 
You are encouraged to listen carefully to your Pastor’s teachings, and strive to keep Advent as much as possible. But it does seem that some leeway in these matters is acceptable.