Hi Ash, welcome! Others have pointed out the importance of knowing the boat, and I can't speak to circumnavigating (we've only been coastal or short 4-5 day offshore passages ... so far!) But living aboard a 33-foot boat for 7 years with another person, I have one tip. There's no such thing as 'real' privacy if you're never out of arm's length of each other, so you must become hypersensitive to what we call "virtual" privacy. (Discuss this with your partner, everyone has different needs and different hot buttons.) You'll hear each others bathroom noises - but pretend you didn't. You'll overhear each others phone conversations - but don't comment unless invited. Most important, no shoulder surfing! If one of you is reading, writing, drawing, or using the computer, absolutely under no circumstances peek unless invited! These walls of courtesy have very effectively replaced real walls, for us.
As for missing friends and family, set up a blog and train them to use email - the easiest way to stay in touch as you travel. If you can afford it, budget some $$ for airline tickets to fly home for [insert your priority here - Xmas, kid brother's graduation, parents' 40th wedding anniversary, etc]. Before you leave, take photos of your friends & family and make a great collage.