@rentechd The current estimation for a fully terra-formed mars does not keep in mind advancing technology at all. Which makes it per definition, the very worst case scenario. I do assume exponential technological growth due to AI and brain-interfacing technologies. Both on Elon Musk's to do list by the way :P

It would likely start by creating a magnetic field, which is the biggest issue to terraforming Mars. The only thing keeping us from starting the process right now. And yes, this could take a long time, but not 1000's of years, likely we'll have the technology in about 50 years or so, then the engineering in 70. Kick-starting the core might prove too difficult to do, but it can be achieved in multiple other ways as you said.
A satellite between the Sun and Mars emitting a magnetic field is the more realistic option in my eyes. But still far from our current capability. The biggest limitations are getting the material there, which the Mars colonization in the coming decades will likely make easier due to breakthroughs in space-travel. And the creation of a giant magnetic field. But that's just a power issue. We just need better solar panels and that problem is likely solvable.

The moment we manage a magnetic field, we'd start creating and spreading human-made bacteria/nanobots to produce the things we need for an atmosphere. Most necessities are already on Mars and do not require asteroids to impact the surface at all. It just needs recombining atoms into the correct molecules, which we are getting much better at at a rapid pace.

Temperatures would rise due to Mars having an atmosphere again.

The entirety of Mars could have an atmosphere in just a few years after having a magnetosphere. Yes we can place plants and animals on Mars to make it look a bit more like Earth, but we wouldn't need those in order to be able to walk on Mars without protection. The bacteria could already provide the function plants have on Earth.