hi missy yes by all means leave the onions whole but ensure they can be cut with your chef spoon before blending, carrots and green pepper go for it. check out the videos here
http://cbm-mick.blogspot.com/ it will give you a heads up on what to do and when seeing it is far better than reading it.
would despute the use of worcestershire sauce in any curry not very BIR imo, hey what do i know...lol and also many pooh pooh the use of any form of lemon in a madras, having witnessed it first hand in 3 restaurant kitchens i think its a given a bit like the chilli powder mixed powder , tomato paste/puree, base sauce and fresh coriander!
it's a simple as that now all you have to do is cook it LOL

kind regards
gary