Every single DSLR will have an Auto mode that's good enough for your needs. Yes, Sony A58 got slightly more elaborate auto mode than the competitors (in a matter a fact it actually has two auto modes: green and orange) but for a vast majority of photographs - it won't make a difference you'd ever notice.
A58 got one advantage from a perspective of someone totally new to the photography in it's EVF - you can see how more-or-less exposure will look like on a final photograph before releasing a shutter, and that really can help you avoid over/under exposed pictures in difficult lighting conditions (eg. when you shoot someone in a shadow on bright, sunlit background). Though to fully take an advantage of that - you'd want to learn how to use exposure compensation.
Something that will make a difference for your low-light pictures and a speed of autofocus is lens. You'd probably want to do one of two things:
- Buy bright (f/2.8) zoom lens and use it as your primary lens (you can leave kit at home or just skip it all together and buy body-only) - for example new Sigma 17-70mm f/2.8-4 HSM C ; Sigma 17-50mm f/2.8 HSM or Tamron 17-50mm f/2.8 - read some reviews and look up the prices to see what you can afford.
- Buy a prime lens on top of your standard kit. I'd recommend one of the 30 or 35mm f/1.8 lenses (for Sony there's excellent Sony DT 35mm f/1.8 SAM) - shooting prime lens is a lesson on it's own, but it'll give you results you won't be able to achieve with a zoom, and shoot in much worse lighting conditions than with standard kit zoom (f/3.5-5.6).
Lenses and lighting in general are two keys to the photography.