50% of light speed is alot. So it might not reduce too much, but it would certainly happen. Specially if you consider collisions in the way there. Even a small fragment would hit the ship as a bullet or worse.
Exactly. Everything wants to follow a geodesic (a straight line in curved space) and Earth is pulling your geodesic inside it. I think this is the best explanation I've seen so far:
I don't know if this was posted earlier since part 1 is from last year, but they just released part 2. If you like Cosmos, you'll probably like this one too: