This all looks like great advice, I'd just add that a phone call should be encouraged whenever you feel you have a suitable relationship with the recruiter to call him/her directly. Especially if you're rejecting a company that you could see yourself working for/with at a later date. A phone call is much more personal, and has the added benefit of being more "final". While an email-reply chain can drag on for days or weeks, a phone call can normally settle most issues in one shot. Some people find a phone call more unnerving but I actually prefer it to agonizing over email wording, sending a long email, and waiting for the asynchronous reply that may never come.

Note that I have very little experience in the job market, this is more just a social recommendation and reflects some feedback I got from recruiters and friends who have been in this situation.