Originally Posted by eternaltransit

1) If you have your onward boarding pass then you can cut it down to 1hour before departure - the premium security/immigration lane is usually empty and you can be through it in 3 minutes
2) Yes
3) No - but after you pass through customs, instead of turning right to Chauffeur drive, turn left and follow the economy class passengers, go right down to the end past the taxi rank towards the Dubai Immigration office and you'll see a Baggage Service center - they can store your baggage for you for a nominal fee (c. 20AED per piece).

I would honestly skip the J lounge breakfast and go into Dubai for a decent one then come back for a shower, change, lunch then your onward flight.