Visitor visa - originals? translations?

[obormot]

I would like to invite a close family friend for a short visit (about a month). This is a retired lady (70 years old) from Russia.
I am EU (non-Brit) citizen, working in UK on permanent contract with good salary, home owner (the guest is a friend of my mother, who lives with me on EEA2 residence card).

The prospective guest has very small pension, but gets some help from her adult children.
I am writing a letter to UK consulate, to say that I will cover all local expenses (food, logging, tourism, entertainment), as well as plain ticket and visa fees. I can send my pay-slips, letter of employment, bank statements, mortgage info, etc - but should I send originals?? (except for the letter form my job, which I ask just for this occasion, I'd prefer to send copies..)
I can send a copy of my EU passport and my mum's EEA2 - should I certify those copies somehow?

Finally, it seems she also should bring documents about her pension, birth certificates of her children, information about those children' jobs, their statements that they support her, etc. Those docs are in Russian. Am I correct that all this should be translated in English with "certified translation"?? (Is not it that consulate workers should know the language of the country!?)
Could it be me who "certifies" translation (by just writing that this is "accurate translation" and signing with date and my contact details)?

Is there something else those people in UK consulate might demand??

Thank you!

[obormot]

Ups.. I tried to post it on "General UK immigration" sub-forum, but somehow it went here. Can it be moved?

[MPH80]

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