1) How is Marshosaurus related to other theropods? Is it a coelurosaur,
carnosaur or spinosauroid?
I've heard it suggested that it was a primitive Allosauroid, someone even
suggested it was close to the sinraptorids once, I thought.
6)Is Eolambia still considered a primitive lambeosaurine?
No. Refer to-
Head, J.J., 2001. A Reanalysis Of The Phylogenetic Postioin Of Eolambia
caroljonesa. Journal of Vertebrate Paleontology 21(2): 392-396
Head points out that the cranial synapomprhies (absence of premaxillary
foramen, partial enrollment of premaxilla around the external nares, and the
absence of paired maxillary rostral processes) are not actually present in
Eolambia. He then goes on the state the character "high neural spines on
caudal vertebrae" is invalid because they occur in Ouranosaurus and
Bactrosaurus, which he believes are not lambeosaurines. However, wasn't
there a paper in which Ouranosaurus and Bactrosaurus were indeed considered
lambeosaurines, in which case, this character would not be invalid? And
then he states that the expanded "foot" of the distal ischium is a
plesiomorphic character found in Camptosaurus, Iguanodon, Ouranosaurus,
Gilmoreosaurus, Bactrosaurus, and Lambeosaurinae.