Thanks for this.
Yes I am doing it in Book View as under normal circumstances, I don't have to mess with adding paragraph formatting as Sigil does it automatically. I suspected this might not be an issue with Sigil.
I'll raise an issue about the first point.
As to the second point: I've tried copying in raw text in the past by having a blank line between paragraphs and this works fine if my text is wrapped in the text editor. But if I have a text file which has hard breaks at the end of the line and is not wrapped, Sigil will create the paragraph but merges the end of the previous line with the start of the next line.
e.g. I "getthis". I should "get this". This means I have to go line-by-line to find all the merged words.
Looks like I might need to do most of my editing outside of Sigil, I was trying to move away from that and get the basic book structure complete within the one tool. Not to worry, I'm sure Sigil will mature to the point that it will be the one-stop-shop I need for this. I'll still keep using it as it is an excellent program and am (in general) loving the way it works.
BTW, never used Notepad++, I normally use Edit+. Might give Notepad++ a try and see which is better.