My name is Dan and I can assure you that if the kit is by Tamiya you have a fine specimen on your hands.The seam problem can be solved with something as simple as white glue applied with several thin coats, with each coat being allowed to dry before applying the next one. Once dry you can sand with very fine sand paper being careful to sand in the same direction as the planks from bow to stern.
This kit really does not seem to have any real weaknesses,but keep in mind the Musashi was built at Nagasaki shipyard and appears to be painted a darker gray than the Yamato built at Kure.Tamiya offers the version of the Musashi as she appeared at the time of her sinking on October 24,1944 at 7:15 pm, with a slightly different anti- aircraft armanent as her sister.
You can moterize the model but I would advise against it.If moterized you will have to add hull support braces,figure out how to remove the entire aft section on a regular basis to service batteries, moters,etc.This increases the likelyhood of damage to the delicate superstructure and other fine details.
To the Musashi's credit she was better designed and built than Yamato.The Musashi took 19 torpedos in the belly and twenty five bomb hits before the ships defenses were overwhelmed and the damage control teams could do nothing more to save her as she slowly sank into the abyss.
I would consider purchasing extra fittings such as railings and ladders as they turn a great model into a fine showpiece.
Good luck,God bless you and Merry Christmas
Sincerily Yours, Dan