Can you help me understand this...?

English is my second language so the sentence structures in literary texts confuse me. I have some questions about these sentences and Thank you in advance for helping me.

1. There was a gritty yellow soap in one corner and a piece of flannel stained with a blue bag in another.

I know the first part, the second part i don't understand, the flannel was stained and it was in the blue bag?!

2. And plain to be heard in the early quiet was the sound of creek in the paddocks running in and out of sandy hollows.

What does the writer mean by plain and creek in the paddocks? and what is hollow exactly?

3. Even that she left lying,

Before this sentence, she finds a comb, does this mean that she left the comb on the ground?

and even that is like even though or it's something else?

4. Zoom! zoom! a bluebottle knocked against the ceiling; the carpet tacks had little bits of ref fluff sticking to them.

These two sentence are supposed to make sense together? i don't get it!