Should my horse be shod or not? Please help!?

My horse is 15 years old and has never been shod. She is a Tennessee Walker and has a naturally smooth gait. I'm not sure how she will do with the shoes, I just got her. She rides English, Western, and bareback, but I only ride Western and bareback. I was also wondering if I don't get her shod will she get thrush more easily or founder. Also, will she be able to ride on the road? And on concrete and stones for a short period of time? Thanks for the advice!