HTML is enabled in the forums; I haven't looked into signatures though.
Second, check your profile under 'Edit Options'. You can define what kind of editor you want. I for instance, prefer the simple text box with no buttons of any kind. The WYSIWYG editor hates it when you Copy and Paste from Word, too. Copy to Notepad before you go to it, and any problems you have vanish.
Third, you've been given mod powers and access. If you don't have moderator powers in the R&D and other technical forums, tell me. I'm not quite too sure I got it right (it's late...)
Fourth, images look fine from here...