If you can book in either Perrache or Part Dieu then it probably originates in Perrache and booking there will give you a jump on all the people who will pile on in Part Dieu. Double check the times but Perrache will probably be 8 minutes or so earlier. PD is a very busy and small (for all the traffic) station with virtually no seating so while Perrache is generally a little run down and unloved in spots I would definitely book there.
The rue Victor Hugo is a pedestrian shopping street and a wide easy place to roll bags down to the station. Watch for the traffic on cross streets. There a couple of decent bar/restaurants just across from the park as you approach Perrache so kill some time there if you have to before rolling to the station.
Follow the colored tracks on the sidewalk for the SNCF trains - kind of a blue/green - to that train tracks. Perrache is currently (always?) under construction so follow the signs and expect diversions. I would allow a solid 10 minutes from the station to the tracks because it can be a ways.
Enjoy Lyon - if not the train stations,
=Tod