I'm pretty new here and haven't yet had any sales but I did a great deal of forum reading before deciding to use Alamy for my back catalogue which I am working through to upload, I also have a bit of background in web SEO - given my short time here I wont be offended if my opinion is disregarded but here goes.
Quantity and Diversity - your image standard is high but the quantity and diversity is low - it seems this site is very much a numbers game.
Tagging - I think the 'discoverability' thing is misleading and probably leads to actually damaging your search results if you end up tagging for the sake of it - every search engine I have ever worked with that uses tagging penalises listings that use vague or irrelevant tag - for example you tag Ambassador a lot - a user here searching using this term is not looking for images like yours - your tag should be about the content of the image only and not about the photographer. Tags should also be in English, that is how searchers are encouraged to use the site. Things like animals though, I would tage with, common name, latin name, and any nicknames etc. In short Tag about the content only, tag in english.
Processing images for Alamy can be time consuming with captions and tags and can slow you down a lot in getting your images online, I would strongly suggest the following - do your captions and tags in your DAM (Digital Asset manager) and make sure they are copied to the IPTC fields that Alamy reads - then upload by FTP - if you do a good enough job then they will go straight on sale when they pass QC and you can refine them later in Alamy image manager if you wish.
So for my workflow I will take a set of images with common values - taken in the same location or same event etc and then in my DAM (ACDsee) I will select the them all and then on mass apply tags that apply to them all and usually a generic and relevant caption that is accurate for all but not highly specific. I will then select the images in smaller groups applying keywords on mass that are relevant to all the images in that group, and so on getting smaller and smaller groups. If I am short of time I'll just FTP them all to Alamy at this point and then complete the final bit in Alamy image manager after they've passed QC, but I find it faster in my DAM - I Then flick through the images one by one adding a bit of extra image specific detail to the caption if appropriate and any tags that apply only to that image then send them up by ftp. Once they pass QC in Alamy I then add all the optional stuff like category from my laptop whenever I have 10 minutes.
as they say 'finished is better that perfect' - but in alamy context perhaps 'on sale is better that perfect' - you can always fine tune as you go.