Ariel Camacho is still "The King"

It's not as simple as "laminated = sh*t". Solid tops vibrate more freely, project more, and mature with age; laminated tops project a little less but withstand bumps and climate changes better, ideal for rough use. For recording or for the guitar to 'breathe', look for solid; for your first 12-string or for everyday use, a good laminated one will do the trick, BE CAREFUL not to be fooled, there are laminated guitars and then there are laminated guitars.

The top arches up ("gets a little belly") and the bridge lifts because the 12 strings pull with enormous force, and over the years, a poorly reinforced top will yield. This is prevented with well-designed bracing, a reinforced bridge, and a factory-installed Bridge Doctor, in addition to maintaining stable humidity.

A twelve-string guitar goes out of tune mainly due to the enormous tension of its 12 strings, new strings that haven't settled yet, changes in climate, and a poorly cut nut. This can be controlled by always tuning 'upwards', stretching new strings, maintaining stable humidity (45–55%), and using a guitar with an adjustable truss rod and a nut cut for paired strings.

To string your twelve-string guitar without trouble: change a few strings at a time (never all 12 at once) so as not to suddenly release all the tension from the top; respect the position of each pair as they were originally; wind evenly and downwards on each tuning peg; stretch each new string by hand and retune several times until it settles. Always use the correct gauge (pair strings 10-47) to avoid straining the neck.

To change your 6-string armonia strings: do it when they look dull or sound dead. Remove and replace them one by one (or a few at a time) to avoid suddenly releasing the tension, winding evenly and downwards on each tuning peg, leaving a little slack, cutting off the excess, and stretching each new string by retuning two or three times. The tuning is standard (E-A-D-G-B-E), so it's easier than with a 12-string guitar.