Yes to flash the other bank, boot from bank1 and then flick the switch to bank0 (with something non-metal) before you initiate the flashing sequence. EvoX will be fine for flashing.
X2 5035 has some nifty features like a config file stored on the HD for live configuration of this bios on bootup. Note that this BIOS will make a right mess if flashed to clones of the DuoX2 - so be ABOLUTELY SURE you have a genuine DuoX2 before flashing it.
I always use X2 4981 on v1.0 - 1.5 and EvoX M8 Plus v1.6 on v1.6's with DuoX2's.
There is a good reason for this and it is recommended by a lot of people, i forget why though! I would stick with EvoX M8 Plus 1.6. I'm not sure why you would have problems with IGR..