Ok,
My 1.1.3 iphone is factory sealed. Has never been even touched.
Ive downloaded the ZiPhone with GUI to proceed.
All I want to know, is if i NEED to downgrade my BL to 3.9, or I can leave it in 4.6.

Thx!

Its more of a personal pref whether you want to downgrade it or not, you don't need to for a jailbreak/unlock but it is available to you as an option. Also not sure if apple checks the bootloader if something ever happened to your phone if you took it in for repair, there is a thread around with discussion of that so I would check that out on the forum.