Didn't the Republicans pick up seats in the Senate?
Yes but things go through the House first. Things originate in the House so the dems are going to start originating investigations and voting down things "because Trump." The other side of that is that the dems can't actually get anything through and then Trump is going to have to legislate via Executive Order.
And if I remember correctly, impeachment proceedings start in the House as well.
I've seen "+2" cited a couple of times. I'm not sure if that means two seats gained, or just 2 seats past the threshold for majority, but either way they held control there.
It's 2 seats gained from previous number. Already a majority (51 + Pence). So now a 6 vote (+2 R, -2 D) buffer in case of RINO turncoats.
No, it's gonna be worse. They feel a bit emboldened by flipping the House. If they can't stop it using the same tactics, we will most definitely see a return to violence by the Democrats.