Alternator/plugs/wires/coil Pack Upgrade

[napa67]

Would appreciate some help from the forum on an upgrade I plan to make on my 98 Mustang GT. Car has 60K no modifications but its time to freshen it up a little. The car runs flawlessly but its still on original plugs (wires were changed once about 20K ago by the dealer due to issue when replacing intake for leak problem -they said antifreeze got on them and they were junk). My alternator just went and I am upgrading to a 200amp to supply more power for my audio system. My questions are - Can the stock positive and negative wire for the stock alternator handle the new increased amperage (wire looks to be about 4 gauge). If I upgrade the coil packs to MSD version do I need to upgrade wires to 9mm and if so do I need to upgrade to a better plug or can I just replace the stock ones. If I replace them do I have to gap them differently? Thanks for all your help on this... The car runs like the day I bought it at the dealership so I don't want to upgrade myself into an unecessary nightmare of chasing problems all summer.