Yes. Usually an '01 probably calls for 5w30, and 10w30 is only a little bit thicker but it should still be fine.
No
Not going to work.
NoNo
will a 1999 voyager brain work for a 1998 dodge caravan
No, the connectors for the sensors are different
No fluid, blown fuse, bad pump, plugged hose,
NoNo
the fuse may be broken
It would not work with out major modifications to every system of the car.
An arm and a leg. >.< Usually head gasket work will run you well over $1000.
No, different bolt pattern to the block.
Perhaps resistor packs on blower motors is defective and need replacement