I had similar questions. I'll check you link regarding the contact form.
As for tags, I tried adding a few tags after-the-fact to my sticky post on the home page (using the Motion theme). The tags show up in the editing page, but they don't "stick" -- when I go back to the site to view it, the sticky post has no tags. (A private test post DOES have tags, which I added at the time I wrote it.)
Also, when I'm trying to add tags to that post, if I click on the link for "use most common tags", it says that the tag list is empty! (Even though the private post did successfully accept tags.)
Can tags only be added at the time of writing? That seems awfully confining.
Thanks for your Time, Thief!