My husband is a roofer, he said that a dipped rafter is practically impossible to straighten - it should be supported by a prop in the attic off a solid wall. Crack in the chimney can be fixed with silicone - if you use sand and cement it ll probably crack again. Moss on the tiles can just scraped off. The gutters again need to be siliconed. He said its a few days work (depends on whether a detatched, semi-d or terrace house) and in terms of price, cant say without seeing but less than two grand at the most.