>> Can we make changes at the subscriber?
Yes, you can do changes at Subscriber.
>> will the changes made at the subscriber get updated at the publisher?
No, In order for changed done at Subscriber to get updated at Publisher, you have to go for Merge Replication only..
>> Is it the same with Snapshot replication too?
Same with Snapshot replication too. Merge replication alone can update a Publisher based upon changes in Subscriber
