Re: plug cap doesn't fit plug
Some of the plug tips are very tight but I've never seen one that wouldn't unscrew with a little effort, the right tool or both. Try visegrips or better yet, leave the plug intact and replace the kit supplied plug boot with a good quality automotive item available at any auto parts store. You'll get the boot and a metal terminal that can be crimped or preferably soldered to the plug wire and will fit the sparkplug without removing the end cap.
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"