How big is Roca ? Is it the biggest Russian church, does it still exist ?
Yes, the Russian Orthodox Church Abroad (ROCA) does still exist. Regarding size, she has roughly: 340 parishes, 26 Monasteries, 14 bishops, 360 priests, 100 Deacons, 150 monastics, and 100,000 lay people. She is very, very small compared to the Russian Church inside Russia (Moscow Patriarchate), whose own numbers even in the diaspora are comparable to ROCA's numbers. This page
might be of some help to you. Fwiw, I think Archbp. Averky of ROCA spoke about the antichrist more than Met. Philaret, so you might want to look around for stuff by him as well (e.g., on Google