The copyright remains in effect for 70 years (in all countries that are signatories of the Berne Convention, i.e., most countries). They become part of your estate and your heirs own them.
In the US, there’s the issue of whether the copyright was registered. You do have the copyright protection if it’s not, but it would be harder for your heirs to punish infringement.
Literally anything and everything you write - blogs, posts on message boards, grocery lists, hate mail - is instantly copyrighted as soon as you put it in tangible form. Nothing is public domain. You can assign rights in the form of a creative commons license so that no permission to reuse is necessary, but at 70 years plus life the very concept of public domain has essentially been abandoned for modern writing.
I doubt a grocery list would be copyrightable in the United States, whose law requires the work to have some creative originality. A mere collection of facts (e.g., a list of things to buy) would not meet this criterion.
Recent editions of it are. Older ones may have lapsed into the public domain.
No, it isn’t. It contains facts, but it isn’t a mere collection of facts; the selection, arrangement, and presentation of those facts required a nontrivial amount of creativity.
See above. Selecting which words and senses to include in the dictionary, and writing the definitions, requires significant creativity.