What might the capitalization of the word "church" indicate? Does capitalization of the word "church" matter, or is it more of a personal preference?

It is obvious why the Bible or Christian is capitalized; they are proper names. A lowercase bible may refer to a reference book, manual, or textbook. Christian is capitalized, presumably because it is a proper name for follower of Christ.
The Church is referred to as the "Bride of Christ" throughout the NT. It's capitalization simply reflects it's status as a proper noun, subject to capitalization.