I have some questions to filers to Ukraine.

Do you send any originals to your fiance?
and if so, what type of mail service do you use?
I read somewhere that we don't have to send any originals of the financial documents, that we can scan it and just email it. So can a scan of the tax returns could be sufficient. I actually obtained transcripts from the IRS so they are offical documets from the gov. Also, what about the boarding passes, I send a copy with the petition, so do I have to send the orginal

Any help from people with experience in the Kiev embassy will be appreciated.

I don't know about Kiev, but the general process for Moscow, and it seems, most other embassies, is to send copies with the petition, then the originals to your fiancee to take to the interview.

Not 100% on the way Kiev operates, but at some time in the VJ process, USCIS will see copies and originals, so you can't go wrong sending copies first, and if they want originals, they'll send an RFE. Just ensure that when the little lady goes to her interview, she as all the original docs, just in case.