My question. If I add a line to get this for $99 can I switch it to my primary line and switch that phone to this line as a dumb phone and pay only the $10 a month for the dumb phone added line and keep my unlimited data on my primary line?
If so, I could also get the Nexus for .01 cent but not crazy about not having hdmi out and worse battery life.
No, you can not do it. If you add that phone, you will lose unlimited, and be forced to choose a new share plan. It will cost you $40 for smartphone, and $30 for the dumbphone you would attach to the new line. PLUS whatever level of data you want to use, from $50 to $100.