Hi Mary,
I'm a fellow native (American) just starting to look for my ancestors who lived "across the pond" too. Unfortunately, I can't really offer any great advice just yet; but a fellow did respond to one of my queries awhile back.... His name is Alastair M. Cameron & he's a professional genealogist. He has a website you can check out at: http://quozl.netrek.org/cameron-research/
I haven't ordered any research through him or his affiliates, so I don't know what quality of work he and his colleagues produce; but he might be worth keeping in mind if you can't break through your brick wall. We've exchanged 2 e-mails in the past couple of months, so I do know he doesn't take an aggressive approach. He might also be willing to offer you some advice on where to look next.
In regards to the questionable dates, I'd say it's best to keep them all in mind. Discrepancies of dates & locations ( & surname spellings ) seem to be one of the hazzards of this type of research. There are a few other web sites I've found that I'll be glad to share if you wish. The caveat here is that I haven't spent a great deal of time searching through their web pages yet; so they may, or may not, prove to be helpful.
Guess that's enough for now. Take care. Good luck and happy hunting!!!
Karen