I think there are always large cultural differences when Americans watch British tv program(me)s and British watch American program(me)s in terms of interpretating what is said at times. I literally saw nothing odd, rude, disparaging etc with anything that Jaleel said to Len or anything said geared towards Roshon. I read these comments before I watched the show and was expecting the worst and wondering whatever it could have been that he said? , but I found he was gracioius, complimentary, and grateful for the experience. I just did not see anything out of sorts..

If anything I would have interepreted it as a gentle ribbing. Little brother sort of thing..
That said, it's no secret this show is partly about fan bases and connecting with the audience. Melissa certainly has a long standing fan base going back to the 70s. Plus while growing up and marrying, she was in several mini series throughout the 80s and 90s, so she is well remembered (and probably loved) by a large demographic who watches DWTS. US spanish language tv stations such as Univision are huge huge huge and I'm sure that is where William gets a lot of his fans. The American hispanic demographic is very large and nothing TV execs want to lose.
I like Katherine (but I have not liked Mark in quite awhile.. since Kristy Yamaguchi I believe lol),, and as good as she is, I'm not sure she has a large enough fan base to keep her at the #1 spot. American's wont keep Melissa over Katherine to be sure, but when it gets to the final 3 and 2, I honestly think Donald may have a serious chance of taking it, or at least Maria and Derek.
I honestly think it's going to be Katherine, Maria and Donald in the final 3, with either Maria or Donald winning. Katherine may be up the #2, but I think Donald, if continuing as he is, could certainly take it. I think the average viewer in this country 1. loves a football player or sports person, 2. loves someone who rises from a lower level to the top , and 3, charms the audiences and connects. His exuberance and perception of trying harder and reaping the benefits is infectious. I don't think the average viewer is looking at the technical aspects of the dance but rather just want to be entertained and see a good (as they view it) dance. Just my little fun speculation...
I certainly loved Katherine joy in seeing Derek & Maria take 3 10's. You could tell she was genuinely pleased for them. When I saw that, I liked her a whole lot better.