Translation:The flower bloomed yesterday.
Thanks, I received the skirt from "my older sister." But there is noone in the village.
Because the を particle indicates the direct object. 花 is not being acted upon. It's the thing doing the act of blooming, therefore を cannot be used here. The が particle is used instead, because this the subject marker.
Blooming is more specific than flourishing. A flourishing plant is just thriving, healthy. A blooming plant is flowering.
You don't. Singular and plural are not clearly distinguished for most Japanese nouns, so both need to be acceptable answers.
It's not really a 'gah!' sound in Japanese, it's more of a nasal 'nnnga' at the back of the mouth, with a really faint g. So it has a bit of an n sound to it that you might mistake for 'ha' or 'wa' too
Depending on your accent, you might do something similar when you say 'singer' in normal speech - if you can make the same sound without the 'si' bit (and end it with an a sound instead) that's pretty close! Depends if you already say that word with a pronounced g though
Blossom should be added as a synonym to bloom.
"The flower blossomed yesterday."