Dual language learners: What educators need to know and how best to deliver language training

From the folks at Early Ed Watch, a US-based blog and part of the New America group (a public policy think tank dedicated to advancing ideas to advance the US), comes news of a 4-part series on dual language learners and what early childhood practitioners need to know in order to best support 2nd (and subsequent) language learning, while maintaining home language(s).
Looks like a useful and interesting series that came out of several key questions; questions worth looking at from a Canadian perspective too:
What to call children who arrive on new shores speaking a language or languages other than English? Early Ed Watch is using “dual language learners”, but “English or French language learners” is used in Ontario/Canada and because programs used to deliver language training are called English or French as Second Language courses, some children are referred to as ESL or FSL children. What do we think? Should we adopt “dual language learner” in place of the awkward E/FSL?
Are dual language learners at risk of performing more poorly than their peers who speak the dominant language of the school community? In the US, there is evidence to suggest this is true. Do people know of any Canadian research in this area?
What is the best way to teach another language? Are there best practices known in Canada? Is immersion the best way? Comments and resources are welcomed.
immigrantchildren.ca will be following the Early Ed Watch series.