I am using a Dremel cordless multipro 7.2 v. Trying to drill a hole thru a steel mount. It aint easy, takes a loooong time. DO I always use higher rpm??

The motor heats up - do I wait between drills or is it ok to heat up?

How do I know when to change drilll bits, do they ever get blunt?

If there is too much friction /obstruction the motor stops - unless I turn off and ON again. Is this normal?
[Last thing I need now is a broken dremel - atleast that works unlike my plane!!! LOL]

When you remove pieces of balsa from the engine-cowl area , what do I coat it with so as to stain it? Can I leave it alone - wonder what would happen if fuel or oil, grease etc come in contact and will that ruin the wood...?

Thanks
747