...Spanish language graphic novels?
I am not an expert on Spanish Language graphic novels, but they are certainly available, as this link to Brodart's collection shows.
...yaoi and/or yuri manga?
We review quite a few BL titles here on the site, so please read our reviews for recommendations.
If you're looking for a great list of both types of titles to check out, please check out the list several colleagues and myself compiled for our 2010 presentation on Yaoi and Yuri for GBLTQ readers, hosted over at Deb Aoki's Manga at About.com blog. Also, for more in depth discussions of these titles and the two subgenres in general, please check out the transcript of our panel Deb edited and posted -- a million thanks.
If you're curious about collecting such titles for your library, here's an older but still hopefully useful basic article on the subject I wrote for Library Journal: Romance by Any Other Name. Sadly, many of the titles mentioned here are out of print, but the basics are still valid.
If you want to get specific recommendations tailored to your preferences, please fill out this form and we'll see what we can do!
...the specific comics issues I'm looking for?
This is one of those times when Wikipedia is, in fact, a great resource (as Wikipedia often is for pop culture.)
Example: the issues and collected editions of the recent Cassandra Cain Batgirl comics. It's just so clear.
If you're looking for a run of particular comics series or a way to figure out which collected editions feature which comic book issues, I direct you to check out Wikipedia. They almost never fail me, and I admit, if you email me and ask, I'll likely just look it up on Wikipedia. So give it a go yourself!
...whether this manga is considered shonen, shojo, josei or seinen?
There are two places I check the original intended audience of manga -- Anime News Network's Encyclopedia and Wikipedia. Search for a title in both places and you should have your answer. Both sites are reliable for these questions and generally allow me to figure out which magazine the series was originally published in and thus which target audience the series was originally aimed at.
Now, who reads it in actuality and who reads it in the US may be different from the original Japanese intention, but if you're looking to define the origins, then the marketing categories are defined by what magazine the series was serialized in for the Japanese reading public.
...a comics creator to come and speak at my library or school?
I do not have any more connections than anyone else to the comics industry, so I fear I have no significant pull with the various comics creators out there.
However, I would suggest that you contact your local comics shop! Comics shops frequently host creators of all kinds, and the staff will know who would suit the purposes of your visit and the age range of the audience. If you're not sure where your local comics stores are, use the Comic Shop Locator.