Is there any way to import the entire "help" namespace from wikimedia into my installation?

I wish there were, but as as far as I can tell there isn't. I've been gradually manually adapting help and tutorial articles from wikipedia and meta for my personal wiki, but there's a lot of manual adjustment. I find that some of the stuff applicable to the wikimedia projects needs to be changed for my needs. I need to carefully read everything to make sure. It's not just the help namespace either, some stuff is in the project workspace, and some is in meta. I've been trying to make my help pages as self contained as I can, minimizing interwiki links to wikipedia, mediawiki, and meta.

There has been some work done to make the help articles semi-portable between the mediawiki projects. Most claim to be copies of generic help articles from meta, with project specific templates used to add project specific material. My impression is that this is still a work in progress though, and it still doesn't help all that much in adapting to local wikis.

Also, a word to the new from the experienced. I'd recommend that you read and understand the wikipedia style guide before going too far in populating a new mediawiki based wiki. I made several mistakes like using initial caps for most words in article titles. This works against the style of using initial caps ONLY for the first word and proper nouns in the title. It' snot a fatal mistake, but you end up using the pipe syntax in links much more than you'd like in order to make a link fit into a sentence in an article body. Another mistake I made in my wiki (which focusses on manned spaceflight) was to use pseudo namespaces like Mercury: and Astronaut: this too works against both the link syntax (for example I'd need to put in [[Astronaut:John Glenn|]] instead of just [[John Glenn]] as well as making sorted lists of articles less than useful. So I find myself now going through and fixing up all these newbie mistakes.