What did the union know, and when did it know it?

I've been thinking a bit about this latest immigration raid in Laurel, Mississippi, and I have a lot of questions.

ICE certainly seemed to stir the pot by stating that a union member's tip a few years ago set the raid en marcha. AP has been pushing the line that workers cheered as immigrant workers were hauled away, and the head of the Mississippi AFL-CIO didn't help matters by calling Laurel a little Mexico

One post at an anti-immigrant forum, apparently from a union member at Howard Industries, sees the raid as positive for contract negotiations:

Yeah, I work at Howard Ind. and ICE finally came!!! It was awesome. Helicopter, hundreds of agents, made my day. . . I.C.E. finally enforces our immigratin laws at Howard Ind. in Laurel, MS Not sure really of the exact numbers working at Howard's but it is well over a thousand for sure. All I can say is it is about time!!!!!!! . . . We are currently renegotiating our contract with the company and with all the non-union illegal aliens that WERE working here we didn't have much of a foot to stand on. WE DO NOW!!!!

David Bacon, as always, has a refreshing perspective, arguing that the raid was an attempt to divide immigrant and Black communities, and that IBEW was stepping up to the plate organizing immigrant workers into the union.

So this is what I want to know:
1.) Many reports give the impression that most union members were Black and most immigrants were non-union. Is this true?
2.) MSM also gives the impression that immigrant workers were getting overtime, and union members weren't. Were they on the same pay scale?
3.) If immigrants were on a different pay scale, what pay scale are new hires at Howard Industries receiving?
4.) How common is it for union establishments in right-to-work states to hire immigrant workers to weaken the union? This is a brilliant tactic, since most unions don't have a culture of educating their own leadership let alone members, and so would be very slow to respond to the challenge of organizing these Spanish speaking invaders.

I have yet to see anything directly from IBEW on the matter, and have no idea how serious were their efforts at organizing the immigrant community. But in a situation like this, if you are serious about building power with immigrants, you need to spend tremendous resources educating all communities involved, and you have to build trust by building power among the immigrant community outside the workplace as OTOC did in Nebraska. [1, 2] The main impression I get here is one of seething resentment, not one of an organizing drive on the verge of a breakthrough.