Basic questions on Texture object bounded to FBO

It is known that FBO has a series of attachment points. If 4 color attachments are added and to each attachment a texture object is associated, are following true?

Q1. Can two different format textures of same dimensions be attached?
i.e A LUMINACE and RGBA of say 256 * 256 ?

Q2. Can two textures of different dimensions but same type attached?

Q3. Can two textures of same dimensions, same type but different target types be attached ? i.e one as GL_TEXTURE_RECTANGLE_ARB and other GL_TEXTURE_2D??

Q4. The specification of FBO tell us to specify atleast one image. Now is this true that a texture can not be attached or associated to COLOR_ATTACHMENT_EXTi+1 if COLOR_ATTACHMENT_EXTi remains empty?

Thanks all.

Q1 & Q2 - these are illegal for EXT version of the extension, and legal for ARB (and 3.0)

Q3 - there is no restriction on texture target types afaik

Q4 - yeah, as i understand, you are free to pick and use any color attachments you like (up to limit)