looking for install instruction for valve leather and the weight that is attached to it?

Mine has a bolt and nut attaching the weight. The ring part of the valve just sits on the base of the pump and is held down by the top 'plunger' section.

does one install it smooth side down (toward water source) or up?

I've always put the smooth side towards the top of the pump, away fro the water. I'm not too sure if it really makes a difference though.

Will this fit the Simmons 1160/pm 500 no.2 pitcher pump?

I'm not sure what all models it fits.... but seems to do fine with the pump we bought (though I couldn't tell you what model it is... it has been a year or more since we purchased it.)

Will this fit a columbiana 2088?

I'm sorry I don't know. Call your local pump dealer. That's what I did. They repaired part of the pump but I had to order the valve. They gave me all the info I needed to order the correct valve. And the name of the company to contact. Good luck finding what you need.