To make a room warm you need to simply balance the heat loss with the heating. If you've done what you can to minimise heat loss then maybe consider larger radiators.
If the house is rented and there is a problem then speak to the landlord. I'd be most annoyed if my tenants started smashing the place around to fix a door if i hadn't been given the oppourtunity to fix it first.
If it goes to court look at appointing an independant expert witness to confirm that the time taken and cost is unreasonable. Deleting emails in bulk in hotmail is incredibly easy if you know how and takes minutes not hours, this is on the assumtion that you can get into the account.
I'd want...
As it's a bungalow I'd be more inclined to add a sun tunnel into the middle of the hall. Probably less effort/cost in this instance as well and they can be very effective.
What is it blocking with? I'd try to change habits and put less fat and waste food down there in the first place. A simple strainer over the pub hole might resolve this.
Could we have a photo please? I personally would try to get 25mm ply with a 4mm channel cut out where the conduit sits, I don't like packing as it might allow movement/squeaks in the future, I also don't like MDF!
The roof may once have been adequate with slate tiles (just!) but with concrete tiles I would say it is grossly underspecced. Personally, I would crack on and get this resolved as soon as possoble. If you are looking at a loft conversion then why not get plans done and strengthen the roof...
Given that information I would not cut it, turning off the gas at your meter may have no effect on this pipe, especially if the building has been converted into flats (the seperate meters for each flat would obviously had been put in after the lead pipes).
It is unlikely that the pipes are...
Almost certainly old gas lighting pipes. If your meter has a copper pipe coming from it then they are almost certainly dead, however it would be wise to pop a floorboard up and try to follow them to their source.
Draught is probably the biggest heat loss here so sort that and you have resolved a big chunk of the problem. You could pop some of those fibre boards that are used under laminate flooring under your ply, that would have a minor insulating effect.
I think I would put reclaimed floorboards on...
I sell software for a living and have a Mac, the easiest and cheapest way is using VirtualBox in my opinion - I do this often.
However, bear in mind that you will need a full license for Windows, which ever method you select.
I've drilled into plenty of Victorian walls with an SDS drill without fear of them falling down, how bad a condition are they in?
In my mind its better to use a powerful SDS and make the hole in seconds rather than spend ages putting pressure on a non hammer bit.