As above it's all about momentum and knowing when you're just not going to progress anymore when keeping doing the same thing.
Last night I had to drive round several cars on the road into our estate as it sits on a hill. One even in the exact same car, sitting hammering the accelerator wheels spinning away.
I don't tend to give it any kind of welly unless it's a complete last resort as I find it rarely gets you any actual traction, best bet is to try and crawl away, if you find the wheels are just completely spinning then rock it back and forward to free them off. Generally speaking once I'm moving I won't get stuck.
Going down hill just don't use the brakes unless you absolutely have to, if it's compacted ice then the car will move around a bit but you'll be going slowly so just keep calm. I've honestly never found a need to turn off esp or the likes, though it'll do little for you when it's so slippy
Winter tyres as mentioned would probably get you going, but my experience of them is that they can't do too much on compacted, icy tracks (still better though).
When it's like this I only really drive the 107 if possible, as it's tiny, light and has tiny tyres - all of which help it get about. In saying that the fn2 was OK but still a big difference between the two