Right distributor for an engine?

I have a 1978 ford Ranchero with a 351 midland in it and when I had the distributor changed my camshaft gears teeth broke so I got that fixed and then 8 months later with only putting exactly 1,067 miles into it the gears broke again and I'm pretty sure the distributor caused this because it had unusual scrap marks on the teeth so even though I might be wrong what's the right distributor for this type of engine

ECU remaps. Are they worth it? Is there a discernible difference in performance?

Hi. I have a 2013 Mondeo 2.0 140 and have read a lot of stuff about remaps. It seems they improve performance and fuel consumption. If true, why aren't Ford selling their cars with ECUs already programmed this way? What am I missing? I'm looking at a Bluefin DIY kit, but before I drop on something I don't really need, I wondered if anyone had any useful pointers, thoughts or ideas. Cheers!

Is this a common problem for this car?

My mom has a 2005 Mercury Grand Marquis with about 110,000 miles on it. It was having an issue (we didn't know what exactly) so we took it to our local Ford dealer Tuesday and we found out last night the transmission went out. People tell me all the time that these cars last over 200,000 miles, but considering that we don't have that many miles on the car, I was wondering, is this a common problem for this car?

Added (1). Also, should we get it replaced? We found a place that can do it for $1,600, and the car is worth about $3,300.