Definitely the southern cross (upside down so to speak). Not sure about the names of the other two. I have always just known them as the pointers as they are used in conjunction with the cross to find south.
Yeah, that would be Alpha and Beta Centauri. They're actually quite prominent, especially Alpha Centauri.
Alpha Centauri is actually a double star (won't be visible without a telescope), one of the two (A) is 50% brighter than our sun, the other (B) half as bright, so the pair put out twice as much power as the sun. The pair is the nearest
visible (to the naked eye) star to the Sun. (There is another star, a red dwarf that can only be seen with a telescope, called Proxima Centauri, it actually orbits Alpha Centauri A and B making it in fact a triple star. It's actually noticeably distant from the other two as seen from Earth, and it happens to be nearer to us than A and B are, so it holds the crown for nearest star to the sun, period.
Beta Centauri is also a triple star. They are a lot further away (~90 times as far) and intrinsically brighter by far than Alpha Centauri. (All three are spectral class B with a color temperature of over 20,000K.) Between the three of them, they belt out 66,000 times as much power as our sun, mostly in the ultraviolet.