Best lens for night protraits/quick captures

Hi everyone,

I've bought a NEX-5 this week, and only have had a few chances to use it but have been a bit underwhelmed by the night performance. I'm coming from a Panasonic TZ-7, and I really like getting candid pics of people I'm with, which is usually at night. This means hand-held shots in low-light settings; obviously my lack of skill has a lot to do with it, but I haven't been getting the shots I want from the NEX-5 as of yet (using the kit 18-55mm). So;

• What settings are best for low-light handheld shots of (slow) moving subjects?

• Autofocus or manual focus?

• Obviously using things like ISO3200, widest aperture etc?

• What lens would best suit this purpose? I wouldn't need zoom for this.

• ie. Small, wide, fast!

• Since we can use any lens via adapters, I'm a bit lost on this :o

• How well does manual focus work with non-E lenses? Especially at night?

I figure I can have one specific lens for this and use the kit lens for everything else (when I have more time to compose and stay still etc) until I feel I have the skill to move on to something better.

Thanks very much!