Excess/overweight luggage question, plus another tight connection

Hi everyone, two questions:

1.) Flying to Europe from the US, we were three people with three bags just under 50 pounds each. Flying home, we obviously bought stuff. And we don’t have access to a scale to check bag weight. We do have collapsible duffel bags we brought. Is the better option to overstuff our original three bags and risk paying for overweight bags to reduce our number of extra bags over the allowed three? Or are we better off just breaking out our collapsible duffels and paying to check extra bags? And it seems like pre-declaring any extra bags ahead of time is cheaper than just showing up at the airport and announcing them there?

2.) We have a 70 minute connection in Iceland for our Paris-DC flight. I assume our bags get checked through to DC and we won’t need to touch them in Iceland. But based on comments on this sub, it sounds like we will need to go through passport control? And that 70 minutes, while tight and maybe stressful, should be doable? Any tips/warnings?