The fact that you don't know the difference between editing and copy-editing speaks volumes about what you don't know about publishing. Editing is a valuable contribution to the publishing process and can make the difference between a mid-shelf and blockbuster book.
The trick of publishing right now is that editing (and to a lesser extent, copy editing) is much less common than it used to be. Editors pick up titles, give them minimal once-overs and turn them over to production because the money isn't in fixing, it's in producing, and they want to keep their jobs. There may be a few editors who have the power to really involve themselves, but they're the exception and not the rule anymore.
Marketing is anything but free and can even fail disastrously for a well-written, well-edited book.
Very true, but again, the reality is that except for a small percentage of books published today, the publisher does very little in terms of marketing. Before he was an e-publishing powerhouse, Joe Konrath used to boast that the only way he made it where he was was by traveling around the country doing his own marketing. He's been self-made the whole time, because publishers largely don't care to do that kind of legwork anymore.
I know several author friends who have been duped into spending all of their advance (or more) to hire THEIR OWN marketing experts to get the word out, because publishers will usually say "get a blog and good luck." It's absurd and short-sighted, but it's the way the game works now, except in very rare circumstances.
If your expertise is writing - which it obviously is or you wouldn't be trying to publish a book, right? Right? - what makes you think you're also an expert marketer/artist/graphic design/layout artist?
This is where we agree 100%. Free templates and buddies who are artists are poison to your work. If you don't know EXACTLY what you're doing, don't do it. A less-than-stellar cover will sink your book before it's opened, and less-than-stellar book block design will ruin your chances almost as fast. To date, there is no magic button to design a book without a lot of expertise.
One final note: if you self-publish, good luck ever getting a reputable publishing company to look twice at you.
This is true, and it's a danger you have to deal with. That said, the question is whether you WANT to work with a publisher. Put quite simply: sign a deal for anything less than a blockbuster title, and you will probably come out of the experience in debt, with so few copies sold you'll never get another book contract again. At least with self-e-publishing, you'll know how much of a raw deal you're getting in advance.