I guess that the 25K miles is for the whole trip, you will only get the miles for the outbound flight which you can use later for the return flight, check how many miles is needed for an upgrade, if you got that then go ahead and upgrade to Biz .


And yes it's always better to check-in at the airport, just book a seat that you think it's good for you and then upon checking in at the airport ask for an exit row seat, if they are taken then go ahead with the one you have booked. On Manage My Booking the exit row seats are always unavailable, you can only book it at the airport.


Hope you have a nice trip and enjoy.