2 basic questions about the Moon

Hello, I can't seem to find the answers to 2 basic questions
about the Moon. Is there an astronaut or someone like that who
could help me out?

(1) Why are the mare almost all on the side facing Earth? I've
read they are perhaps ancient lava flows (but not from a volcano
I guess because there doesn't seem to be any volcano in the
middle of them?) And it appears from the Apollo photos they are
brownish in direct sunlight if you are standing in the middle of
them? And what color would the highlands be, grey? And (sorry
this is actually several questions) what is the surface like
walking on the Moon, it is hard and crusty or rather like sand?
Is the latter why it was so difficult to plant the American flag
and why it fell over?

(2) (Shorter question) If I straighten out the Earth's
revolution around the Sun so it's a straight line, what curve is
the Moon's motion along that line most similar to, perhaps a
sine wave? I know it's actually an incredibly complicated curve
but that's the general shape of it, i.e. there are no little
loops or sudden changes of direction?

Thanks!