Journal abortion in ext3 and its relation with remounting

I was looking at the code of ext3 file system and found some strange 
implementation there :

Can someone let me know the validity of below statements and with 
reasoning :

1. I found that it might also happen that journal is aborted but not 
re-mounted
2. Journal gets aborted but it might be possible to mount it in 
read-write mode.
3. Can we write some data on the partition where journal is aborted.

One more question, how unlinked inode is handled by ext3 ?

Regards
Shubham