RAFVR Research (For Screenplay)

Hi everyone - not sure if this is the correct place for an enquiry around RAFVR bombing operations during WW2, but it's for a screenplay I am planning, around a true story concerning my grandmother's cousin who was a Flight Sergeant in the RAFVR.
The gist is this - that Alan, who piloted Wellington IVs, in 1942 had nearly completed his tour of 30 ops, but on the last flight the observer was unable to locate the target, and so he turned back, and landed at Grimsby with a full bombload. He was obliged to fly again to complete his tour and was shot down on the infamous raid on Kassel where many aircrew were lost.
So, does anyone know the answers to these questions:
a) Landing a Wellington with a full bombload - this sounds dangerous, but I don't know how the bombs were fuzed - was this as dodgy as it sounds?
b) I was told by Alan's widow that most pilots would drop their bombs over the sea if they didn't find the target, and the flight would count towards the tour total. Is this credible? I understand that the crew would have to provide photographic evidence that the bombs had been dropped, so dropping them over the sea may not have counted anyway?
c) How often would bomber aircrew fly: was this likely to be on consecutive nights or nearly consecutive nights if the weather was good? Or would they spend days and weeks waiting to fly again? What did they do in the meantime?
d) Did airmen stay together as a team for a tour, or did they get allocated to different crews over the course of the tour? Did the pilot keep the same aircraft, assuming it was airworthy, or were they allocated different aircraft?

Thanks for your help!