"Trandafir" comes from the Greek "τριαντάφυλλο (triantáfyllo)", meaning thirty leaves, or, as we could have said in Spanish, "treintafolio".
It is. In Bulgarian, while 'rose' remains the word for a rose, the word "трендафил" ([trendafil]), although sounding a little outdated, is still used for a special kind of bush, larger and branchier than a rosebush, whith slightly different flowers. In Romanian it simply means 'Rose'. You can check how the name of Led Zeppelin's album 'Paper Roses' used to be translated in socialist-time Romania - 'Trandafirii de hartie'.