What would you do...advice on spraying and seeding

Ok I need to work on a few fields, two are primarily hayfields and one primarily pasture. Im going to spray for weeds this fall, maybe October. I have too much toxic fescue and too many weeds like ironweed. I mowed the ironweed a few weeks ago. I want to fertilize, control the weeds, drill some orchardgrass and maybe some timothy this fall, and frost seed red clover in Feb.

I was thinking of fertilizing in September and spraying the weeds in October once they have a little mire regrowth on them from the late summer mowing.

I have ironweed...if I used crossbow (triclopyr) would that endanger the grass I drill?
What about red clover 2-3months later?
Should I just use 2,4D instead.
When should OG be drilled in the fall or would you wait til spring?
My fields are very low in potassium 57ppm. Should I put on the recommended potassium all at once or some this fall some in the spring. Same with nitrogen, or do all that in the spring?

What would you do...advice on spraying and seeding