chapel renovation

I need to repair some chapel windows around a property I purchased earlier this year. I could do with some advice on 1) what wood should I use to repair any rotten window sections? Would standard B&Q softwood be ok here? 2) What should I use to replace the gap between the window and the wall...

I realise that this is a very specific case and I appreciate any advice that I can get. I know that the topic of internally insulating solid stone walls is a recurring one but with all the contradictory advice I was hoping that I might be able to get a consensus on the best course of action in...