Ignition Key Problems

For my 1995 Aurora, I have for some time been having flaky starting problems. Sounds similar to other things posted here. For example, when turning key to start I would hear a few clicks and then it may be 2-3 seconds before started would engage and start engine. Lately now, in some cases it seems as if the starter does not disengage when key release. On occassion, the starter will engage even when key is turned to on position.

Is it time to have the key llock assembly replaced. Is that what is reffered to as the ignition switch, key lock, tumblers or what? Is that a DIY or does steering wheel & air bag need to be pulled. Thanks.