Thanks for posting this list, it's a good starting point although some points may cause confusion.
1. Generally it's quite hard for people to determine what style of wedding photography they might want, without having seen some. A good start is to simply and casually take a look around at what is out there. Also seek recommendations from friends who have had wedding photography done (of which you thought the result was of a high quality). General approaches may bring a fashion style to wedding photography, which would require a bit more posing and set up. The other popular approach is a bit more photojournalistic, as they say, and candid. From there you can start breaking it down to photographers who have a style of their own.
2. Regarding the level of service, this would make more sense in terms of do you want preparation shots, do you want the photographer to stay until the end of the reception. Or if you have just a small gathering or elopement, do you just want the ceremony and a few shots afterwards. All of our clients get an extremely high level of service, the main variable is what we photograph on the day rather than what service we give.
3. Deciding how many images you want - not really the best train of thought. The best photographers do not shoot to fill quotas. Have a chat to the photographers you are considering and ask them how many photographs they generally deliver from a wedding. I usually tell my customers the average as well as the least and most I've given.
4. Do not process the images yourself. It's part of the photographer's vision for the images when they are taken. Processing the images yourself is like buying material from a wedding dress maker and then cutting and sewing it all yourself. If you have a preference in terms of editing/styling then talk to your photographer and choose a photographer who's work really appeals to you. Chances are it will appeal to you in part because of the treatment of the images after they are taken. We typically spend about 3 - 4 hours editing per hour of shooting, not because we take bad photos, but because we take great ones and we like them to be perfect.
5. Yes, work out your budget, then find the best photographer you can afford within that - not the cheapest. If the best is the cheapest, then you've got yourself the cherry on top.
6. It's worth thinking about what wall space you have free in your home and what you would want from an album, but this is again something to be discussed with your wedding photographer. It's also hard to make plans for photos that don't exist yet Once you can see all the photos from your beautiful wedding it will become a lot easier to determine what you want and where you want it.
7. Prints, Digital Files, Albums. Don't ask for RAW files, the sound important but they require photographic editing programs to open. No good photographers give these out either.
14. This is a good point. If the photographer doesn't have backup plans or liability insurance then it may be worth giving them a wide berth.
15. You should determine what photographers are available on the date a lot earlier than this, to save you time. Why research and interview photographers who aren't available?
17. Your spouse to be should be part of the whole process, not just briefed on it at the end.
19. Your photographer will expect a booking fee to secure the date, this is standard and is a small insurance for them as they will need to turn away work for the same date, even work worth a lot more money.