First off, how can I make the system accept posts without a name?
Secondly, I can't seem to be able to post without a tripcode (neither on my nor on the "sample" ochiba imageboard)
I advise against posting without a tripcode - it eliminates the ability to delete your own posts. If you must, you can give it the same treatment as above for the name.
Secondly, for some reason or another, my imageboard at http://pinkweb.org/p won't show any picture preview... also, worrying :P
This looks to me like a problem with permissions on your thumbs and img directories. Make sure they are set to be writable by the web server processing. From a shell, you could do
if your directories are in the web server group, or
as a last resort.
Lastly, and probably my greatest problem - I can't seem to be able to reply to any posts, no matter what I do, my replies get bunched in the respective sub-board. Also, I would like to get rid of the entire "category" interface in the post window - how would I do that?
Hmm, your ochiba install isn't working quite properly - have you made a lot of changes to it? First of all, I see that the reply links do not include the parent post/thread ID number. If you hold your mouse over a reply link and look at the URL in the status bar, it looks like
with the ID missing. There should be a number after the "id=" part. You can look at the test boards here and see what that should look like.
Secondly, your posting window is not normal either- yours has the site menu for some reason, and does not automatically select the category depending on what category you were looking at when you clicked the "post" link. Again, you can go check out the test board and see that the posting window should not have a site menu, and should automatically select the category based on where you are when you clicked it. This addresses your 2nd item - if this feature was working, you could eliminate the category choices.
Anyway, my suspicion is that modification of the ochiba code has led to the loss of these normal functions, so I would advise rolling back your edits or re-installing ochiba and being more methodical about making changes so that you don't lose these features.