If we were to engage in climate engineering, warming things up and adding a little CO2 is exactly what we'd want to do.
It would increase the range of latitudes for food production and mitigate future ice ages, which are much more catastrophic than any effects from warming.
Wrong on all counts. Temperature is just one of many factors when it comes to growing food. Just because it's warm enough to grow something doesn't mean it will actually grow. For example, you aren't growing jack on top of the giant granite block in Canada known as the Canadian Shield. In addition, crops also depend on day-night cycles and would have no protections against pests and destructive species in the region. And what about water? In that shiny new latitude do you have any aquifers that can support major agricultural operations?
Starting major agricultural operations isn't something trivially done, and there aren't a hell of a lot of places in the world that actually have the conditions and/or resources to support it (let alone species adapted to those regions).
And no, ice ages are no more destructive than warm periods. Historically climate shifts, either warm or cold, were accompanied by extinction events. Life adapts to current conditions, and if those conditions suddenly change then more often than not that life dies. Just like sheets of ice, heat can easily make regions of the planet practically uninhabitable.