A change of control of Ford would likely trigger a default under Ford's debt, at which point it must be paid back. So if you are not financing with debt, an acquiror would really need the $150bn EV in order to afford to acquire the company. Of course, in reality, an acquiror would either replace such debt with new acquisition financing or work out a way to keep the existing debt in place.

DCF is indeed a method to estimate the fair value of a company's EV, not it's market cap. People will usually do a DCF, then subtract net debt in order to get an estimate of equity value from the DCF. Here's a citation: http://macabacus.com/valuation/dcf/overview