Wimpy by Steve Bond isn't bad, but I wouldn't bother with the other two, unless you are after crew stories.
Two books that I think are more suited to what you are searching for Jukka are:
* Vickers Aircraft Since 1908, by C.F. Andrews.
Great technical detail, design, uses and development of the Wellington. And because it is part of a' development' saga, the how and why it was developed (following on from the Wellesley) and where it progressed to (the Warwick and the Windsor) is all part of the story.
* Wellington Special, by Alec Lumsden.
Along the same lines as the Vickers book. Although not is such depth, as it does also delve into the crews who manned it. But it does have very good, if somewhat brief sections on technical performance, origin of the geodetics design (strengths and weaknesses), production, people, cockpit and controls, and types numbers and marks.
A third book that is right up your alley is (unfortunately I don't have it) is:
* Vickers Wellington Manual: 1936-1953 (all marks and models), by Iain Murray.
I have the Haynes book on the Lancaster, and it is in the same vein as that of the Wellington. Will give you all the technical detail you could wish for - construction, production, engines, uses, development, performance and so on.
