[Q]flashing 4.3 stock via odin topic

1. My note 3 came with 4.4 bootloader and modem. Now Can I flash 4.3 stock via odin? Will there be any problems?

2. I was wondering if I can flash custom Roms based on TW 4.3 even though I have 4.4 bootloader.

Any help and tips are appreciated.