A different word count question - I promise!

An estimate will do just fine. Word count lets them know approximately how long the manuscript is, but also how many pages they could expect the final book to be (depending on formatting, of course). Chapter titles and quotes are part of that.

1. Any word that takes up page space counts.

2. Estimate. Round number. 86,643 = 87,000.

If you skip the quotes, chap heads, and breaks, or include them, you should end up with pretty much the same number. But since they are really worried about pages of books, in principle you really ought to include them.

Agents and editors are trying to get the "shoe size" of your book. It isn't a high-resolution number.

The only real question is whether you round to the nearest thousand or the nearest five thousand. Most people use the nearest thousand. In something the size of a typical novel, it doesn't matter. Telling someone your word count is 92,284 will not only label you as an amateur, but as a dweeb also.

It's like telling people you're five-foot nine and five-eights inches tall. More info than they need, and also really kinda, well...weird. Don't stress about it. It won't be that length when it's published anyhow.

Different word count methods give different results, anyway. I think we all know by now that the traditional 250 words/page in Courier 12 gives a very different result than MS Word word count. But I've seen a test comparing OpenOffice to MS Word; those came out slightly different, too. I don't know about WordPerfect, but it wouldn't surprise me if it gave yet another result.

Publishers only care how much paper it will take to print, but that's for your agent to deal with. I strongly suspect agents, at least at the query stage, are primarily interested in finding out whether you have a clue. They just want to weed out the 30K or 300K 'novels'.

Stop worrying about word count differences of fewer than 5,000 words.