In the process, is it necessary to verify the Ubuntu download prior to installation - its a bit complicated for me! ;)
If you are worried about the download not being correct: yes. It is very very simple.
Secondly, is there a way to know whether my computer hardware is compatible with 16.04.3?
If the live session starts without issues, set up wireless. You can then play around with your system and if it all seems to work generally the normal install works too. Besides that: if 12.04 works 16.04 is likely to work too unless you got really really old hardware.
You can also write down all your hardware specs and have a look on the internet. Generally the 2 components that need attention are the video card and the network card. If the video card is AMD or nVidia you should be fine. If the network card is intel it will be fine. Broadcom can be a challenge.