For songs I recommend using Karafun. It cost $6 for two day access. $10 for an entire month. They have software / app for your computer / phone / tablet. You'll need internet access but it doesn't use a lot of data so you should be able to use your phone's data plan if needed.
For a PA system I recommend something like this. It's simple to set up and operate. But if you're uncomfortable buying from Amazon I recommend going to your local music store like Guitar Center. They can show you an equivalent system.
I recommend using a direct connection (use a cable) from your device to the PA system instead of Bluetooth. Using Bluetooth introduces an undesirable delay.