Hello, I Would Like To Design

Hello, I would like to design my own robot vacuum. For starters I'd like to develop a robot that can first map out a room, then navigate around it using my own algorithm and later recognise that room. Later on I'd like for the robot to be able to navigate across obstacles like stairs, recognise people's presence, notice changes in a room while still knowing it's the same room, move stuff around with his hand, scare away my cats etc.. I am 26, fluent in C# and am very interested in this stuff. Please help me choose the best parts or a kit to get me started properly. Thank you!