You can use the +/- to go up and down 'gears' manually including driving in 2nd if you like. No reason it should be any worse in the snow because of being automatic, but I don't know what Jazzes are like anyway.

Winter tyres again and there's a good chance it will be comparable with the Fabia.

In M (manual) setting you should be able to change every gear yourself within reason via the +/- lever, so the only difference will be how smoothly you can engage power compared to a manual, with practice it should be every bit as smooth...which is more than can be said for automated manuals and some dual clutch set ups.

Winter setting usually by passes first gear entirely, you can parctice in M to see if you have that option, whether it helps i'm none too convinced to be honest.

Obviously unless you fit winter tyres the car isn't going to be a patch on your Fabia.

I suspect in practice the car will be perfectly fine left in auto provided its on the correct tyres, hopefully you are able to disable traction control or ASR whatever its called on your car, doing so can hep get the vehicle moving when in dodgy conditions but remember if you don't turn it back on again then you are in complete control and the TC or it's equivalents won't be doing their part to overall skid control.

As with all these things, the best policy is to learn your car intimately regarding this before the bad weather arrives, then you'll know exactly how much engine braking control you have etc.

In late January this year we had a blizzard locally and I had a Fiesta petrol auto as a courtesy car while my Volvo was having a warranty job done.

The Fiesta was very easy to drive on the snow in auto because the low-speed creep in 'drive' was perfect for setting off in very slippery conditions without needing any throttle input at all.

I was able to get up hills at walking pace and navigate between dozens of abandoned cars (including some fat-tyred 4x4s) without difficulty, simply by leaving the box in D and focusing on the steering. That was without winter tyres too, so with winter tyres I think you'll be fine.