Write the query letter and send it, then wait for a reply and then actually start the whole writing process. I'm not interested in hearing whether this is right or wrong. I just want to know if it's doable. Thanks.

All Answers To Questions

No. No. No. NEVER. Especially if you've never been published before. Finish the book, THEN send the query letter and wait for a reply. They won't be interested in a book that doesn't exist yet.

If you don't have a finished product no agent or acquisitions editor will give you the time of day. Why? Because 99% of people who say they would like to, want to, or are going to write a book never actually (a) start and (b) finish.

no... manuscript is important..

No it's not, I highly doubt any agents or editors would be willing to accept a book that has yet to be written unless you are already signed on for a series which would mean you would not need to send out a query letter again.

Possible, but as likely as you winning the lottery on 3 separate occasions. It has happened but only once or twice in history. Also, if you were to actually be accepted, they would be wanting the manuscript ASAP. If you can't get it to them quick enough, you'd be out of luck. If you've never written a book before, this is really not the way to go... if you have written a book before, it's not the way to go.

Only if it's a non-fiction book and you are an established expert in the subject. If it's a novel? I doubt they'd even bother answering. Do you know how many million people think they have a wonderful idea for a novel, if only someone would pay them to write it?

If it's non-fiction and you're recognised as an expert on the subject, then yes, you can do this. It's expected, even. If it's fiction then (assuming you don't admit that the book isn't written yet) in theory there's no reason why not. Publishers and agents seem to take so damn long to make up their minds about queries from unpublished writers that it can seem very tempting. In practice, Murphy's Law says that your query will magically migrate to the top of the slush pile, and the person who reads it will love it and want to see the book right away. You then have to ask him to wait, at which point he assumes he's wasting his time with you and heads off to an awards ceremony (filled with people he hates, but hey, the booze is free). This is one reason why they always ask for a synopsis of the complete book. That doesn't prove that the book is finished, but it raises the chances of that being true. For the record, when I was querying for an earlier novel, I sent out queries to five agents (not enough, I know...). Three responded (all with rejections :-( The first one (by email) came back the next day. The second, also by email, came back in about three weeks. That wouldn't have left much time for writing if the book didn't exist yet. The third, by post, took about ten months. The agent I queried had left the agency to set up on his own, and I suppose they'd put everything addressed to him that wasn't from people he knew into a drawer in a back room. They did have the decency to apologise for taking so long. Make of that what you will.