Need to try any shoes on for proper fit and comfort. May need to go a size larger or smaller. Your regular shoe size is a ballpark start and you may have to consider buying a separate pair of shoes for winter to accommodate thicker/warmer socks. The bottoms will be stiffer than a regular shoe for the reasons DieselDan mentioned.

Personally, I find the lack of widths in cycling shoes to be my main problem with fit. Some of us need EEE's...lol.