You can do that by replacing the tensioner
the belt is automatically tensioned by a spring loaded tensioner.
Timing chain.
Chain
Yes.
you dont belt is self adjusting one of the puleys is called a tenteder belt or tenteder may need repacleing
yes
The belt tensioner is rotated clock wise with a 15 mm wrench or belt tool.
it should automaticly tighten when you release the tensioner pulley after putting the new belt on. if it does not tighten 1 of 2 things happened 1). you didnt run the belt the right way 2). tensioner assembly is faulted and needs to be replaced.
Not sure ,but it costs $115 to change mine on my 1998 Dodge Durango.
Change the belt
The 1990 dodge caravan has a transverse mounted engine therefore it doesn't have a fan belt!