step 3 of this tutorial https://forum.magicmirror.builders/topic/236/complete-setup-tutorial/6 describes the process for stopping the screen blanking. hopefully that solves that problem for you.
as for the update notice, are you referring to the display alert in the top bar? you can simply remove the call for that module in your config.js file and then it wont display that header at all.
this is a snippet of the default contents of config.js
modules: [
{
module: "alert",
},
{
module: "updatenotification",
position: "top_bar"
},
{
module: "clock",
position: "top_left"
},
you can delete the module call altogether or comment it out with /* */ symbols like so…
modules: [
{
module: "alert",
},
/* {
module: "updatenotification",
position: "top_bar"
},
*/ {
module: "clock",
position: "top_left"
},