I do work in the industry, I am working for Nissan North America right now.
That does help. Being a car nut in a family full of them also helps.
As far as the Chrysler-PSA or Chrysler-BL dealings, those would both face nationalistic issues (particularly with the French), but its possible. The biggest thing which hurts Detroit's international efforts is not finances - they've never had that problem - but ideas. That's part of the reason I always use the Corvair as a POD. If its a roaring success, Detroit would perhaps take more chances and use better technologies and better design for their cars around the world, as well as in the US.
As far as an arrangement between Ford and Nissan or Toyota - which is not impossible, but not real plausible. Toyota did just about go under in 1950, but one should remember that the company at that time was still controlled by the Toyoda family. Selling out to Ford in that case would not happen, especially as there was other parts of the company that weren't going broke. Nissan is more likely to work with Ford, owing to the fact that its founder, Yoshisuke Aikawa, had been heavily influenced by a visit to the United States in 1909, and as he got Nissan off the ground after WWII, he had a number of Americans as part of the staff.
If that deal is made, Nissan would probably through the 1950s assembled Ford cars in Japan, but they would use what they learned there as a base to build off of to make their own cars and designs, starting in the late 1950s and early 1960s. Ford might object to this, but I doubt it. As Nissan's efforts to enter the US market get serious, Ford would probably help them do it, complete with Ford-Nissan dealers in some cases, though this would probably split up on an organized basis by the early 1970s. Assuming they see that they need to make good small cars to run in that market, Nissan and Ford might hammer out a deal to develop better small cars for Ford, which means the Pinto (if its still called that, it might not) would be a much better car. Nissan would never allow itself to sell a car with the exploding fuel tank problem because of cultural concerns - the Japanese have a deep dread of fire - so that problem never comes out.
For your last point, the best way to do that is to have somebody come in who is an engineering guru who wants to keep using technology to make better cars. Having Ed Cole rise to be GM's President would probably do it - Cole was a major backer of the Corvair. Have that car be successful, and build it without the swing-axle rear suspension (a stupid idea all around IMO) but with the independent rear suspension of the 1965-on models, and you'd have unquestionably the best small car in the world at the time - Corvairs, aside from the stupid rear suspension design, were good cars. The car is a major success, Nader doesn't focus on it with his book, and the 1965 model is a similar success. By this point, GM is finding out that fitting many of the Corvair's suspension innovations makes for better cars all around, and disc brakes, which could be easily introduced with the 1963 Corvette, prove to be easier to produce and more effective, thus making them almost universal across the range by 1970. Finding that GM's cars are better than theirs, Ford, Chrysler and AMC undergo a crash course to keep up. This makes for the ultimate musclecars of 1968-1971 also having much better roadholding and ride, and better brakes.
This attention to technology allows for all four American manufacturers to make considerably better smaller cars. The excellent design of the Corvair and its following rivals nips much of the import manufacturer efforts in the bud. They get a foothold after the oil crisis, but Detroit answers the oil crisis with much better cars than in OTL, thus allowing them to minimize the damage done. Over the 1970s, Detroit looks into why people buy imports and discovers the pricing strategy and build quality differences, and applies that idea across their range.
