... what exactly does this mean? I read mixed replies about needing to replace the chain when "x" or just keep the chain until it's at the end of its adjusment. What exactly does this mean? That you can't turn the 2 adjustment screws any further to tighten the chain?
Yeah, the adjustment screws pull the axle back in the swing arm. When the axle can't go back any further and the chain is still not tight enough, it is time for a new chain. You can also measure the links as described in the manual, but the two things are pretty equivalent.