I have just got an EZCAST dongle which works fine at casting data (film, music etc) from my Samsung tablet to the TV.

Is it possible to use it to mirror live content from the tablet to the TV?

Yes it should do. Look in your tablet settings there should be an option for Screen Mirroring and in the list of available devices your Ezcast device should be available if plugged in and working. It can take a few seconds for it to connect and work but it's a great option to use for that.

There can be a bit of sluggishness in the screen update as it's peer to peer wireless but it should work. My Samsung Galaxy tab works fine with it.

The issue seems that when I can only connect wirelessly to either the Ezcast or my router.

The problem seems to be that I can connect to Ezcast but when I try to mirror the Ezcast doesn't show up as a nearby device, although I can cast data to it.

Obviously I want to connect WIFI to my router with the tablet and then cast to the dongle without losing my WIFI connection.

You need to install the Easycast app, this allows you to connect the adapter to your router like Chromecast does.

The android version of Eazycast is utter dog crap though for example when I wanted to enter the code for my router the app wouldn't bring up the tablet keyboard unless held portrait so watch for that.

The iOS version is better.

Chromecast is so superior to miracast devices but does require an intenet connection and a router.

Mirroring on an android is a doddle. More importantly, many apps eg BBC Iplayer, Netflix, Plex, youtube can cast a program and then once started, you can even put android into standby to preserve battery.

Only plus of miracast is you use wifi direct to tv and do not need router/internet, but in most homes these days, hardly an issue. Hand for travelling though if location does not have wifi.