Hari,
Welcome to the forum! I just bought an iLiad and I have been reading a lot of conference and journal articles on it and, for the most part, it works just fine. I don't think it has CHM support so that would require some pre-processing on your part.
I don't have an answer about customs and all because I ordered from a local reseller here in the US (ereaderoutfitters.com) and didn't have any such issues.
Please take a look at
these two threads to see what technical PDFs look like on the iLiad.
Good Luck!