1) You will not get a hotel as you could have chosen EK203 (outbound) and EK512 or 516 (inbound) to minimise the layover time. If you choose to take a long stopover then you are not entitled to a hotel.
2) As above and also first class. Skywards Silver lounge may also have re-opened but I haven't seen a date for that yet.
3) Contrary to the above post, I see from your posting that you are on a Saver Fare and as such the upgrade would cost 57.500 miles one way from DXB-JFK or vice versa.
4) Exit row seats - arrive early at the airport to request these. Ask at the transit desk at DXB for the next leg.
5) Baggage allowance is different for itineraries to/from USA.