Hello Hira, you have described Lawrence's writing beautifully and accurately in your last paragraph. Your first question is hard to answer, simply;and I don't have time today to get into all of that; but will try to later on. But as to Lawrence's fluid and lovely style of writing I feel much the same way you do and I can't put his books down very easily, either.
Unfortunately, we don't currently have an active discussion on "The Rainbow". It is a shame you just missed out on our very good discussion on "Sons and Lovers" - you might want to check out that thread, to gather more insight and information on the book, and it's 'deeper' meanings. A few months back we also, discussed in much depth, "Women in Love". There are many, many posts on that novel in the thread and the thread has tons of commentary and good documented information.
I, for one, am a total Lawrence addict and advocate. I have read nearly all he has written and still have a few books, I am planning soon. I did read "The Rainbow", but it was many years ago and much has escaped my memory; I plan a re-reading of that book soon, probably early next year. Perhaps we can get an active discussion group started in the spring on that book, as well. I know that another forum member, Virgil, loves that book the best; it is his favorite. "Women in Love" has always been my favorite. I have now read it twice and listened to the audiobook (half, so far)...so that will be my 3rd exposure to the novel. It is, in my eyes, Lawrence's masterpiece work. He thought so himself and said as much. The good news is, we are planning a spring reading of "Lady Chatterly's Lover", if you are interested in joining our group at that time. I know it will be a very good insightful group, because interest in Lawrence has been steadily growing on this forum. You can find some of this novels and his short stories and poetry, right here on the site.
By the way, 'Welcome to Lit Net!' You will find this a great forum with very nice and helpful people. I have made many friends here and enjoy it so much, I can't begin to tell you. I have also learned a great deal more about Lawrence as a participant and in reading the various existing posts. There is a lot of biographical information in the three threads "Lawrence Short Stories", "Sons and Lovers" and "Women in Love" - it just takes a little time and searching.
There is also a "Lawrence Baby Tortoise" thread that deals with his Tortoise poems - I think there were about 5 or 6. We will resume that thread eventually and the short story thread is on hold now for one month and will start again in January, after the holidays.