I placed the node outside; thus the drinking fountain is available 24/7.

Yes. From what I recall the defibrillator is outdoors of the main building (not currently mapped - possibly the town hall?) in the central square.

Colehill! Not Coleford.

So how would you record the ground truth version as in the name on the road sign (since the 'name' has the full expanded version)?
Guidelines are guidelines - not mandatory rules - so some flexibility is there for atypical situations.

Um, why did you delete this?
What harm could it be doing?
The 'alt_name' is exactly the text on the street sign.
Also this is the name used in OS Locator dataset and thus useful for comparing OSM vs this other dataset.

The edit is good.

Even better would be to add bicycle=yes & foot=yes as well since cyclists + pedestrians can use this ferry too.

You may want to consider checking at least for 'source:ref' tags.
At least Brunt Acres Road is signed on the road as C32.
From http://www.flickr.com/photos/pobice/3432837568/ back in 2009 and it's still there as of August 2018 when I went past.

A cursory look at other sources such as Bing, OS_OpenData_Streetview & NLS OS:1:25K sources suggest this is a track/service road to an isolated place in the middle of the Welsh hillsides.
Clearly bridleway is closer to reality than an unclassified road, although personally I would have made it a track.

You need to also delete the original amenity=bank tag too.

If you are changing such a large number of things over a large area, please describe the nature of the changes in the comment changeset for future reference and understanding.

I think the postboxes in the Postal Musuem such as:
node/4939823803
Would be better described as historic=post_box rather than amenity to prevent confusion over such postboxes being actively in use for postal services.

No not especially, as I passed by relatively rapidly on bicycle.
Saw some old Yew trees in Powis Castle Gardens the next day though (not mapped yet either).

I believe historic=memorial is more appropriate than a monument for plaques.
A monument is normally something quite big (e.g. the Naval Memorial on the seafront)

Fairly sure I didn't add them, e.g.
relation/5465217/history
However I may try to fix them in time...

Yes indeed I moved it, as can be seen fairly clearly on Bing aerial imagery - which aligned to my GPS trace (albeit that ended on path entrance to the pub garden).
The Code stones are directly in line from that path entrance at the back of the pub garden.

Can you elaborate which actual streets were missing from the 79 ways that have changed from this edit?

Here you seem to have accidentally moved a load of benches and other things including the Southsea Hover Terminal.
Achavi is a good way to visualize what happened here:
http://nrenner.github.io/achavi/?changeset=45694906
I think this edit might best be reverted and then redo whatever actual edits you were trying to achieve around the Ryde promenade.

I'm confused how come you've labelled "DS Smith" Weighbridge as a hospital.

Welcome to OSM.

Just a couple of minor hints -
you probably want to check your spelling ;)

Palyground is normally spelt Playground (this edit and one or two of your early edits)

Capitalization of Wooburn Park might be good on this one too.

Regarding the path way/273654934
It shouldn't have a description as the proper name. This should be moved to either the tag note= or osm.wiki/Tag:description=.
Also it's hard to believe this path has a signposted incline - the area doesn't look that steep anyway.