Deck modification

I have a wooden deck in my back garden that I'd like to modify. The current size is 7mx4m. I'd like to do two things; first cut a section of 1m alongside so the new size is 7mx3m, and second to add an extension forming a path to a summerhouse at the back of the property. This new section should have around 80-90cm width and 5.4m long.