Welcome to the forum and quit the worrying
Like the other folks have said, call the center, let them know you're interested in becoming a member and would like to take an intro class to get a feel for the place.
If you wanna bring a friend go for it but don't worry about not having a partner. The instructor makes sure all can participate. Have had a few times one may end up doing a round robin (2 instead of 3 folks). It's nothing for you to worry about
As for next level, it depends on your abilities, how much you train and so on. Enjoy the journey and you'll know when you're ready to test. Yeah I know upper levels are the fun stuff but without a good foundation, the upper levels don't mean squat. Take it from someone who's been had to start, stop a quite a few times, took over a year for my level 3 test because life got in the way for myself and hubby.
Don't feel bad if you're not in 'perfect shape'. I dont think anyone is when they started. That's what KMs' for - to get you in that awesome shape. Best of luck to you