1. The ethernet / DWDM modules preferred
GE_XPE, 10GE_XPE, OTU2_XP, ML cards,
CE-Series 10-Port Multirate Ethernet Card, 10DME, MXP, 10x10 there are lot of cards depends on your requirement, line rates coming from WAN device, types of module present on WAN side.
2. The typical wave length will be used -- 1550 or 1310?
depends if you looking for a SDH/SONET solution, will say 1550, if DWDM than it will be composite siganal with MUX/DMUX.
3. What are the speeds supported on the modules?
10mbps, 100Mbps, 1000Mbps, 1Gig, 10Gig, 40gig and 100Gig depends on your requirement :-)
4. What should be the recommended max losses / power budget for 130 km for Cisco ONS to work properly?
around 35dB to 39dB of span loss, looks you need amplification.
5. Any specific recommendations.
we need to discuss your requiremnets, there are lot of sloution available.