Delay in MN1 And Need To Travel - Urgent

[intelinside]

I and my wife got ILR on 7th Nov 2013 and after that we applied for our son's registration using MN1 form on 13th Nov. I applied myself without using NCS service so had to send my original passport and ILR, son's passport, his UK Birth Certificate (born in April 2011) and his BRP (due to expire on 2nd Feb 2014).

MN1 is taking ages and now we have an urgent need to travel back to our home country. Now, I have couple of questions related to that:

1. I understand that I can ask for the return of my original documents but not sure what will be the status of my application if I ask for it. Will this cancel my application? No payment has yet been taken though.

2. My son's BRP (He got Tier1 Extension with us on 2nd Feb 2012) is expiring on 2nd Feb 2014, we may come back to UK before this date (2nd Feb) so I assume it won't cause any immigration problem at the airport(?) But what will happen if we return after 2nd Feb 2014 as my son won't have any visa at that time. What would I show at the airport (our ILR and his UK birth certificate?)