september firmware update

[pixeltroll]

Hello, I have some problems with the new september firmware update.
I followed all the manual steps, but it feels that I don't now some important steps.
Earlier firmware updates worked fine for me. maybe I forgot one step?
I not a programer, still an advanced user.
please could sombody help me with the update?
I am an owner of the felix 2.1, on the chip is a sticker named felix 2.0.
Which ardurino board is it? Where can I check the ardurino type?

If I intend to use a second extruder (dual extruder setup) which firmware should I choose?
20141002- FIRMWARE - Repetier 0.92 - FELIX_2_0_SINGLE_extrusion ?
20141002 - FIRMWARE - Repetier 0.92 - FELIX_3_0_DUAL_extrusion ?

The update process brakes with some errors, I will post them here.