I have a JLT 3.0 on my boosted 5.0 Mustang too. On both vehicles, the more/deeper I get into boost, the more oil that is collected.
I check each of them every 1,000 miles to ensure they are not overfilled. For some that may be about 2-4 weeks, but for me that's closer to 6-8 weeks...NOTE: mileage and level of boost you get into are the most important factors for when to empty.
Yes, the JLT system for your specific vehicle is truly a plug-n-play. You remove the old PCV hose and in its place plug in the JLT system. The hoses have the correct Ford connectors...very easy to return to OEM/Factory if you so desire.