Ignition and/or Starter Safety

OK... I need a little help on this... My 3.1 started by turning my ignition to the On position than used a screw driver to jump the starter. It started. I drove home and shut the car off.

Than, I turned the key to see what would happen....It started..

I was told my ignition switch could have gone out...how hard is it to replace it or can I trouble shoot this?

Also, I was told about the switch for the transmition? Is this hard to do too or what does anyone think about this.

Thanks!