1.02 Doesn't actively require any japanese characters, as the default folder name is in english and it doesn't use much aside from that. Just affects the readability of the button labels. Should have been the same with 1.01, though. You might just be pressing the wrong buttons, dunno :V
You use helpers effectively by learning where you "need" to use them, really.
Stuff like Flan and Remi doesn't actually help you anywhere in particular, and you won't learn anything by spamming them, which is why I don't recommend them.
Patchy's also useful pretty much anywhere, but again if you don't take the time to kill stuff you won't learn anything.
Alice and Meiling are good for tricky positioning (stuff below and above you).
You can fire Reimu backwards and hit stuff that's normally out of reach.
Knives are just pretty useful in general until you learn how to dodge well and make use of Sakuya's skillset better.