Merging a list and wildcard expansion in org-agenda-files

["Adrian C." <anrxc@sysphere.org>]

Hello, 
I read the FAQ entry "How can include all org files in a directory in my 
agenda?" and I'd like to merge both examples from the answer for my 
agenda-files.

To include all org files in a directory I would use 
(setq org-agenda-files '("~/org/")).

I have a special projects directory with the format 
~/projects/<projectname>/project.org for that I would use

(setq org-agenda-files (file-expand-wildcards 
~"/projects/*/project.org"))


I tried to define a single org-agenda-files with both, unfortunately I 
don't know a lot of elisp so my tries like using list() all failed. For 
the first directory I guess I could also use file-expand-widlcards with 
*.org, but wasn't succesful in merging two file-expand-wildcards either.


On a simillar note I'd like to pitch in another questions. If someone is 
able to help me, then my agenda view combined would have 30 to 50 files, 
previously I never wondered why all the files end up opened in emacs 
buffers. But now if I combined them all each time I view the agenda I 
will be loading all the files. Any way to avoid opening 30 new buffers? 
Thank you.