Both of those bikes are great. I was looking at a Dew Plus a while ago when one in the local market caught my eyes--700c wheels, hydraulic discs, it's a great bike. You should be able to mount a child seat at the rear with no problem. And hauling a child in the back, definitely a flat or riser bar. I did the same for quite a few years with my kids.

I can't advise you on how to haul your gear with a child in the back. Perhaps a fork-mount rack for the front. A backpack isn't ideal with a kid behind you. Others might be able to advise you better.