compatibility between java and groovy?

I have few questions regarding java and groovy compatibility.

1) I read that both java and groovy source files are converted to bytecodes .class that are run by jvm. Are the compiled bytecode same? I assume so because they are running in same virtual machine.

2) Can i mix java and groovy source files and compile them using one compiler? Suppose a part of application is written in pure java and another part is written in groovy. Can they be combined and compiled together using one compile? If this is possible then then how does compiling work in this case? are groovy files get converted to java files and then they are compiled by javac?

3) If i have compiled groovy and i dynamically linked a java library then is there any compatibility issue? can groovy be dynamically linked to any java libraries among the thousands of existing java libraries?

i appreciate any insights. Thanks!