Some questions on part 2 Summer

Will the shop of part 1 close at the launch of part 2 and it's shop? Or it stays separated untill the end of the event?

Will the map of Part 1 disappear, aka willl I be blocked from farming there the old materials once the part 2 begins? Or they exist separately, with part 1 map still farmeable?

Is it much harder than part 1? Or about the same level of farming? And the main quest fights, also the same level?

Also, Summer Mistress CE gives no bonus in the part 2, right? The other CEs seems to have a part 2 farming effect...