this is really more about getting May out from under that “temporary caretaker government” shadow after Cameron left?
I don’t think she is seen as a “temporary caretaker government” at all, she was the overwhelmingly popular candidate for Party Leader/PM. I think it’s more about shutting up dissenting voices (of all parties) in Parliament of the “Yes we agree you’ve got a mandate for Brexit, Prime Minister… but not this kind of Brexit!” variety. She’s going to ask the country clearly and directly “Do you want a Brexit on my terms?”. The electorate will most probably answer, “Yes please!” emphatically and she can get on with the business of doing just that.
Is my understanding correct that this isn’t really expected to change anything substantive? i.e. the people, parliamentary percentages, policies, etc, aren’t really expected to change much at all
Not really, I think things will change quite a bit because the Labour opposition party will most likely be wiped out due in large part to how deeply unpopular their leader (and cabinet) is, which I’m sad to say is probably for their own good in the medium to long term. Hopefully the Lib-Dem party will get back some seats after they were annihilated at the last election.