Sounds like your cluster is bad. If the odometer is working then the cluster is receiving a signal from the VSS. The cluster is not interpreting the signal for the speedo needle to work but it does for the odometer...Id try a new cluster.

The heater problem sounds like your thermostat. Does your temp guage fluctuate when you get on it and match the heater temp output? If the thermostat is stuck open, the coolant will not get warm enough because its is circulating through the system too quickly. As you get on it, more load, the engine combustion temps will rise and the coolant will warm up a bit...