Cell phones are much tougher than you think. It will be fine in your purse. Many of them live in gym bags under track spikes and live to make calls again. Keep in mind that every high school boy you see has a cell phone. There is no way you will treat yours as badly as they treat theirs!!
Your finger nails won't hurt the keys of the phone. I have long nails and have had the same phone for over two years. Just dial away and don't worry about it. If you really want to get fancy, most phone have a voice dial command. Then you only dial it once and give it a name. After that you just say, "Call Home" and it magically does it.