Well on the last point, although IIRC they were largely from the Parsis minority in India the 1st non-white MPs in the British Parliament were from India in the late 19thC. Also as one hang-over from the Raj a lot of the Indian upper classes especially are English speaking which would make it easier for them to be accepted in Britain and possibly to a lesser degree elsewhere in western Europe as they would be fluent in a language that a lot of other Europeans speak.
Moving tens of millions of people, especially if in the aftermath of a major conflict or an ecological collapse would be a huge operation however and you could see more dying that making it to the end of the voyage.
Steve, you might be interested in this data:
Minorities' Cognitive Performance In The UK - Anatoly Karlin
Here is data from the Cognitive Abilities Test for UK students in 2009/10 via Ambiguous. Some interesting things to take away here: (1) The sample is very large. Verbal IQ has the highest correlation with academic performance in most subjects, followed by Quantitative IQ, and then Non-Verbal...
akarlin.com
British Indians are, on average, almost as smart as British whites are!