Ok you will know the answer, my router says it's 5ghz compatible. Does that make it faster and or stronger?
Also do we need to get new routers/modems to support 5G, or can we still use our current tech?
In regard to your router, wireless routers use two main spectrum. 2.4 GHz and 5 GHz. Basically put, the 2.4 GHz is slower but will travel a bit further through the house. The 5 GHz is faster. If your devices have 5 GHz then you're probably better off using it. You can also mix and match. Put some devices on the 5 GHz and some on the 2.4 GHz to avoid them interrupting each other.
In regard to 5G, yeah. But only if you want to use 5G internet. You can still use the fixed line NBN but if you want to use 5G instead of NBN then you need a new modem/router. Your Telco will usually give you a 5G modem/router when you sign up. If you want to keep the old router then you can usually bridge the connection from the new modem to the old router
The newer phones coming out like the Samsung S20 also have 5G capability.