Would that I did have the money to fly you all out to Oz!
I do second Bob's nomination of TAOS as a great primary source for what it was like in those transitional days from sail to steam. To answer your question; yes, there were two forms of BoT certification available in 1912. One could either aim for a Master's ticket in sail or in steam. However, if you were ambitious and expected to get anywhere with companies such as Cunard or the WSL, it had to be in sail. Sail trained officers were regarded as having undergone more rigorous training and experiences, and were regarded as better all-rounders. The WSL's own training ship, the Mersey, was a sailing vessel, even though the company itself ran steamers. It was only with the war and the shortage of officers in the merchant service with these larger companies (many of their pre-war officers were RNR, and went into the Navy for the duration) that these strictures began to relax and these companies began taking in more steam trained officers. Men like Bestic, for example, were able to get a berth on the Lusitania. I should add that though certification in sail was preferred (and, indeed, a requirement pre-war for larger companies), they also had to have had experience in steam.
Skills hard won in sail, among both officers and ABs, began to atrophy after a while in Steam. I was reading about one of the last great William Thomas vessels the other day, the Metropolis, and a voyage on which she made what was for her a comparatively slow crossing. The crew put it down to her master being a man who had been in sail, gone to steam, and had come back to command a vessel in sail again, the result being that he had lost confidence. Men of the era snorted about 'knocking of the sea and going into steam' or spoke of 'ships of wood, men of iron. Ships of iron, men of wood.'
Of the Titanic's offices, Joseph Boxhall spent the shortest amount of time in sail. There was some anxiety for them when they made the transition - James Moody left a wonderful record of moving into steam. It was clear to these men that this was the future of their profession, as the runs on which sail could still compete with steam were becoming fewer and fewer. So Moody, with the help of his last sailing ship master, simply signed on a steamer after he had earned his second mate's certification. The period whilst she prepared for sea was somewhat nerveracking for him, because, as he put it, there was so much he didn't know about being in a 'hot water bottle', and 'I never open my mouth without I shall have my foot in it.' In the end, though, there were no mishaps and he spent the remainder of his short career, and life, in steam.