Need some advise on a 94 e350 van

We have a 1994 RV based on a 1994 E350 van. First, when driving, it seems that there is "play" in the steering. Looking
at the tires, wear pattern seems normal (even) What happens is that while driving, there is left/right travel iwith the steering wheel. This is probably about 4 inches What would the most likely issue(s) be?
Second, the cab has manual doors locks and windows. What all needs to be replaced to make these more current (read POWER!!!)
Third, the seats are "captains chairs". THese are the most uncomfortable seats I have ever been in. Are there any power seats that can fit in there instead?
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