Help help me with Microbiology Genetics, please!

Measles is a human-specific disease caused by a virus with the following properties:
In the electron microscope, it appears to be a spherical particle with a lipid containing envelope.
ssRNA is detected within the capsid
when purified viral genome (nucleic acid) is added to an in vitro system containing all of the factors necessary for protein synthesis, no proteins are made.
when purified genome is inserted in animal cells, no new viruses are detected.
Sketch/describe a plausible outline for the replication of this virus.  Include the following steps:
Attachment: how might this virus interact with a host cell?
Entry: what is the most likely way this virus enters into a cell?
Synthesis: what are the likely steps that would have to be included to replicate the genome of this virus.  Mention any proteins (viral or host) that would be required for this, and specifically what nucleic acid is packaged into the capsid.
What is the most likely way that new virus particles egress from the host cell?