2007 Forest River Roof Replacement questions??

I had my camper in northern ny for two years,squirrels started to eat the rubber roof and sealant or use for nesting..Question is hoping Im in the right area here.
Took the tpo off and the under layment luan and am left with foam>>
1-Is there any tips on removing the luan from the foam without foam damage...
2 Should I use luan again or 1/4"plywood near the same thickness ply a little more.
3 Whats the best and safest adhesive to use that wont melt the foam..
Thanks for any help...

Man I can believe how cheap these things are built luan-foam-luan only metal support in the roof was near the a/c

2007 Shamrock 25RS

TPO
PVC OR
EPDM ROOF????