What happens if someone piggybacks of my hotspot iphone 5?

I was using my hotspot of iphone 5 via USB and I saw it was 2 connections.

Could they see the photos and contacts on my actual iphone? Also could they see my phone number? Because I ended up getting a blocked call number after it.

No they can't. All they do is connect to a wireless network which is your iPhone. It just appears as a Wi-Fi hotspot and unless you state that the Wi-Fi hotspot is a phone, they won't even know it is an iPhone. If people are connecting to your handphone, you can change your personal hotspot password by going into your settings, click on personal hotspot and change the password. Simple as that. Good luck. Hope no one is stealing your information.