EF maintain transaction and concurrency automatically

1) transaction means when we are adding multiple data to a table then there could be  a dodgy data in collection which causes error. so in this kind of scenario EF will rollback or

suppose we are adding multiple data to multiple table. few data has been added successfully to a table1 and when we add again few data to table2 then error occur. in this kind of scenario full things will be rollback for table1 and table2?

2) concurrency 

suppose user1 open a records to edit but before save a second user2 edit that data. so when user 1 will try to save that data then he should be blocked as per concurrency. does it handle EF automatically?