Hi. Don’t worry about PHP notices and deprecated messages. Just pay attention to FATAL and ERROR, and sometimes WARNING. But anyway, these messages belong in the logs, not on screen.
Which OS are you using, is it Windows? PHP on Windows is particularly picky with these messages, and it breaks to app more.
PHP 7.2.3 is a bit untested with SuiteCRM, probably. There were some work done to make it compatible with PHP 7.2, but this is all quite new.
So my advice is to try it with PHP 7.1 and turn off the errors, and see how it goes.