Greetings from the Great Northwest (Pacific Wonderland... Oregon)
Twelves are great for a wide variety of music, but yeah the tuning is different. Only the B & High E are tuned the same on the doublets, G, D, A,& E on the base side are tuned with the small strings an octave above their doublet paired string.
It is not uncommon to tune down to D to reduce the tension on the strings and like posted above, capo up as needed to get to standard tuning. As the number of strings is doubled so too is the tension on the bridge and neck when everything is up to pitch.
Hence all that good advise. Most instruments are fully up to handling the added tension at standard pitch, but some reports of cracked braces and lifting bridges have been seen... including one of mine.
It is always possible to string it with only 6 strings if you want until you get used to the slightly wider neck and jump that other hurdle later at your option. The silk and steel strings can be a little softer on your fingers, but I have had good luck with Thomastik Enfeld strings as they tend to need less tension to come up to pitch. But it always is good to try other brands and guages to find what is comfortable to you. A proper set-up goes a long way towards a better experience so you are not "fighting" to make your chords. Most times a luthier will include a new set of strings with that service and is well worth the meager fee.
Take Care;
Doug
"what is this quintessence of dust?" - Shakespeare
