At the end of a two-day mileage run itnTokyo, I will be meeting a friend who lives in the Shinagawa area. I have been told I will need to take the Rinkai line from Shinjuku station to the Shinagawa Seaside station. I was wondering if it is easy to take direct trains from Shinjuku all the way to Shinagawa, without having to change at Osaki.

I will also need to get back to Haneda from Shinagawa Seaside. Am I right that the best way to go is to take the Rinkai line one stop to Tennozu Isle, and the monorail from there? How long should I plan for this trip to take? Thank you for your help!