We've successfully went through the process and my Husband has landed. We ended up getting my husband's expungement documents so we submitted them after we applied (about 4 months, after I got sponsorship approval). When filling out the forms, since it was expunged, we put "no" for a criminal record since an expungement makes it legal to say that he's never been charged with a crime. My husband's charge showed up on the FBI check and we submitted the whole application with it without an explanation. Once we had the actual court documents to submit to show everything (the charge and the expungement order), we gave an explanation and it didn't seem to be a problem. I'm not 100 percent on American laws because it varies from State to State, but most of the time if the charge is expunged or sealed, you don't have to admit to it. I would suggest to submit any court records to show that it's actually expunged or sealed and a short explanation of what happened just to shorten and help the process. Sometimes a sealed record will show up on an FBI check as my Husband's did as it's not a requirement for the FBI to update their files according to a particular State's laws since they're the Feds, but if you can show proof of the expungement or seal order, that should suffice.
As for police records from other countries, I believe you're supposed to submit them all when you submit your file. Sure, they may request them at a later date, but that's just going to cause delays for your file since they'll request them, then you submit them. This just opens up another can of worms since you don't know if they'll even receive them by the time they expire. You may send them by courier when you receive them, but knowing CIC, they might not match them up with your file in time (police checks are only valid for 3 months). We were requested to submit another FBI after we applied. It took 6 weeks for us to get the FBI check back and we sent it in. By the time they matched it to our file, it was a day short of expiring (3 months for them to match it to our file). Because of this, they then requested another one and gave us 5 months to do so. About 1 month later they told us to ignore the request for another FBI but our file was still held back for those 5 months. Oh..if I could do the process all over again, I'd do a few things differently!