"all this is new" tells something about the entire or the whole part of that thing which is, new. the "all" here functions as an adjective. "this is all new" would simply mean that the thing is completely new. the "all" here functions as an adverb. therefore, "all" is synonymous to 'completely', 'totally' or 'wholly'. :)

Yes they can be used to mean the same thing.

Yes, these two phrases have the same meaning.

All that glitters is not gold?