every pregnancy is different, my first trimester was horrible with this one yet my others were a breeze. I didn't even have boob pain with my now pregnancy until week 30. Totally normal :)
No it doesnt. It's very common for symptoms to come and go, ecspecialy so early. Some pregnancies I didn't feel any symptoms at all till closer to 7 weeks.
I'm only 4 weeks but have very sore boobs.. However I notice they're more sore on some days than others. I only had it this early on with this pregnancy and my very first. The others I had almost no symptoms until about 6 weeks. I'd say it's normal as every pregnancy is different.