I think a posting suite is several postboxes next to each other. Usually separate boxes for stamped mail and meter mail, maybe also separate for 1st class/2nd class mail.

I think a "drive through" tag would be useful, ie for things you can use without getting out of your car.
I'm surprised their isn't a tag already - not specifically for postboxes, but it would be useful for fast-food places, banks etc. I see there's a tag for service=drive-through, but that's for tagging the road that goes past the business, not the business itself.

I'd never heard of drive-through postboxes in the UK, though I noticed Wikipedia has an example of an American one (with a 'snorkel'): http://en.wikipedia.org/wiki/File:Drivethroughlaneatpostoffice.jpg

For adding pictures, you have to upload them somewhere else - eg to Flickr, Photobucket etc, or to the OSM Wiki or Wikimedia Commons (if under a free licence).
Then just post a link in your diary. Or I think you can use HTML tags, to include the image in your diary.

You could tag it as indoor=yes, to make it clear it is within the building (and not above or below the building etc).
Also, you could tag the building with its opening hours, which will imply you can only use the path during those times.

Have you seen this post on the Talk-GB list: http://lists.openstreetmap.org/pipermail/talk-gb/2010-August/010105.html
It refers to the map here, which is using OSM as a background: http://www.mczmapping.org/

Its an official thing from Defra etc, and it seems they are wanting to get the correct marine boundaries in OSM. So maybe they can supply the official boundaries under a suitable licence.

For the bicycle ramp on the steps, you can tag the way as ramp:bicycle=yes (plus highway=steps etc).
See osm.wiki/Key:ramp

So why did you add it to the map in the first place? What was your source for adding it? Is there a postbox at that location?

I don't think the Cloudmade Garmin maps are routable, are they?

I recommend this website, the maps are routable, and you can pick the area you want: http://garmin.na1400.info/routable.php

Or other options to download from this page, it lists which are routable: osm.wiki/OSM_Map_On_Garmin/Download

Where did you download the map from? What website?
Some OSM based Garmin maps don't support auto-routing, so the Garmin will just use the basemap instead.

See the page on good practice: osm.wiki/Good_practice
Specifically, this section (though worth reading the rest of the page anyway):

One feature, one OSM-object
Don't place nodes in (equally labelled) areas just to see some icon appear on the map. The renderers will display icons on areas as well and there's no need to have every parking-lot, soccer-ground etc. twice in the database.

Yes, its true that some renderers don't show icons on areas for some things, but this is a problem with the renderer which should be fixed. Don't have a node and an area, because that can cause duplicates in other renderers or searches etc.
If you're creating Garmin maps with Mkgmap, you can use the option "--add-pois-to-area", to get the correct POI icons and searches etc.

Or an easier option:
Load your waypoints in MapSource, then do "Save as", and save as GPX format.
You can then open the GPX file in JOSM, and it will show markers where your waypoints are. So you can add nodes on top of the markers, and upload to OSM.

I'm assuming the restaurant is open to the public, not just hotel guests?
One option is to have separate nodes, one tagged as tourism=hotel, the other as amenity=restaurant.
I'd say this is worth doing if the entrance to the restaurant is separate from the main hotel entrance. Also, sometimes the restaurant has its own name, different from the hotel name.

For the village hall, I think the best tag is amenity=community_centre
osm.wiki/Tag:amenity%3Dcommunity_centre
Though I don't think this is currently rendered.

Hello and welcome.
Have you seen OpenOrienteeringMap. Its an orienteering map based on OSM data. http://oobrien.com/oom/

See the contacts page: osm.wiki/Contact
Probably the best place for asking questions is the mailing lists. Specifically "talk" for general discussion, "tagging" for tag specific questions (like this sort of thing), or "talk-gb" for UK specific things, or "newbies" for simple / beginners questions.

You can also ask questions on the forum, but its not very busy, so you may not get as many answers.
Or the IRC channel if you want a more immediate answer / discussion.

As for your question, there is no need for relation for this. The best option is to draw the Tesco building as an area, tagged shop=supermarket, building=yes, name=Tesco (plus opening_hours= etc).
I think the building=yes tag makes it fairly clear everything in that area is within the "lockable confines" of it.

You could specify your sources in the changeset comments, to make it clear where your data is coming from. Or add source tags, to the changeset or to the objects.
Also you could try using the "merge" tool in JOSM, to combine the duplicate nodes, keeping the relevant tags from each. Note you can hold down CTRL and drag one node on top of another to merge it.

It would also be a good idea to use the standard tagging for collection times. See osm.wiki/Key:collection_times

I think a tag for the box type is a good idea, but I'm not sure if there is any standard tag agreed for this. Maybe worth proposing something and documenting it on the wiki.
And a tag for the royal cypher as well?

Try a filter: "-amenity=postbox"
That will filter everything that is not tagged as amenity=postbox.

Or for what you want, something like:
-(amenity=post_box new_upload=yes ref=SG*)

It looks like someone has done a bulk import of government data for land use in Georgia, but not Atlanta (or any other states?).
Its mentioned on this page: osm.wiki/Georgia_%28U.S._state%29#Land_Use

I don't know whether any similar data is available for Alabama or elsewhere, or how useful it is.

For a road with multiple arms, yes you just draw it as multiple ways, all branching off each other. And tag them all with the same name= etc.
There's no need to use a relation for this - if the ways are all connected to each other, its obvious its all part of the same road.
Mapnik and Osmarender can render these fine.

There is some phone software that does rendering of vector maps from the OSM data. eg GpsMid http://gpsmid.sourceforge.net/
Or other options here, the list specifies which do vector maps: osm.wiki/Software/Mobile_phones

Also worth comparing your GPS tracks with the OS Streetview maps - they are pretty accurate in most places. Much better than NPE maps anyway!

Though surveying on the ground is still a good idea to check its correct, plus you can find lots of stuff that isn't shown on the OS maps, eg postboxes, bus stops etc.

Rivers should be mapped as an area (tagged waterway=riverbank) and a way (tagged waterway=river). See osm.wiki/Tag:waterway%3Driverbank

Its not just for rendering, it also indicates the direction the river is flowing. And it could also be used for routing, or measuring the length of a river etc.