In the very end of the article, there are photos of the Telegraph LLC, the company behind Telegram, just a floor below the currently government owned VKontakte
Re: servers - there are several paragraphs in the middle detailing Telegram's DC move to London. So your server farm claim is still unconfirmed.
Re: the office - from what I gather, they maintain a shell company in Russia that sits in the former Telegram office. The photo merely shows that they may have a large office space, which may have been inherited by this company from their VK split for all we know. I really can't tell from this post if they do any development in their Moscow office.