I have spotted with each of my pregnancies. Around weeks 5-7. Cramping is also normal, though if it gets really bad, see the doctor. The reason I was told for the spotting is because around this time your body is used to having a period, so it's trying to have one, but since the hormone's are wrong, it's a little confused. You'll probably spot for a few days and then it'll go away. Good luck and I hope all is well!
I don't know how early they can see the baby on the ultrasound, but I know they can around 7 weeks. That's how far along I was with 2 of my pregnancies when I had my first ultrasound.