I am currently helping a dog rescue out and have installed "Invision power board", when posting a new post there's the option to add an attachment (which I assume allows pictures) but when trying to add a picture to a post I get this error msg:
"The requested file upload failed. This is either because it was not in the correct format, or the file size was larger than that allowed. Please check the file you wish to upload and try again."
However, in the Control Panel, images are allowed to be uploaded in jpeg, tiff, png, etc (I double checked the img is correct format - jpeg) and the max file size is 48MB!!!
Just a thought - some other boards that allow uploads of pictures, require a certain directory to be chmod to 666 or something. It has caught me out in the past, bu throwing up unrelated errors - maybe similar?
As for the linking back to home page, can you not change the logo on the top from Invision to something relating to the site, and then change the header.php code to point back to the homepage?