Freaky,
The back of the seat bolts to the hole thru the cross bar in the top of the rear A frame , it's usually a small piece of angle with an upright T piece or a T shaped bracket with spacing and holes to suit seat height and the front bolts to the little cross piece at the rear of the diamond.
As Slides says, check a couple of other sliders out and work out a seat and height that suits you.
As far as the forks go, wheel out, top cross piece off, and treat each fork leg individually, get them sliding well , then , assemble them with wheel and top cross piece, without damper unit , if they still stick, pull wheel out and see if it is a problem with axle spacing, if still sticky you may have to apply gentle persuasion to get each leg of the H piece parallel.
The bloody things bend like spaghetti and I've torn me hair out more than once to get them working properly, gave up on the last set and got Ray Dole and Peter Campbell to sort them out for me.
Good luck with them
Foss