Pitched roofs are preferable for snowy areas to prevent collapsing but flat roofs are great for rooftop gardens. Though I voted neither it really should be either or both because so much depends on the area and the need.

it's possible to have a tiled or steel roof painted and the product, if applied well, should last for many years and can be reapplied if necessary..like any painted surface...not aware of any other product except these roof paints but, if your roof is already 30 years old it's probably time to have it checked for any potential weaknesses ...what is the roof made out of?

It is just an aesthetic thing, but it would annoy me everytime I see the front portico. It makes the portico look like a poorly considered add-on with differing roof pitches for no good reason. It looks like the new wings either side of the portico will match into the existing house well and will be well integrated into the existing roof structure. You need to decide as soon as possible if you are going to live with it and ignore it, or halt the work on it and pay for new roof trusses that match the other roofs. The more work that is completed on the portico the more expensive it will be to change. In this case procatination in making a decision may cost you big dollars. Best of luck, Dr Retro of Dr Retro House Calls

Could you put a photo please?