Can't go wrong with this board and you can update the cpu if you wanted later as well.
http://www.newegg.ca/Product/Product.aspx?Item=N82E16813131873
As far as speakers, it really depends on what you have had in the past but something like these are decent sound for the money...
20C to 30C is way good especially after an overclock. That cpu runs hot so make sure you double check the temps with another program (HWmonitor for example). If the temps check out, you are golden. I think 62C is the max for the 8120.