Questions about dividing irises???

Hi all,
I moved in here about 5 years ago and there on the side of the house was what I thought was daffodils. A ton of blooms.
The next year I realized they were actually irises; bearded irises. There were less blooms.
This year there were only about 2-3 that bloomed.
I learned from forums like this that they have to be divided every few years. I doubt they have ever been divided. Also the place they grow gets shadier and shadier every year.
So today I go out and start digging. First with a shovel, then with my hands. In less than an hour I pulled out 116 iris with fans of various sizes and a whole lot of "train track." Some of the track was even overlapping other track. Some of it has roots, some not. I cut the leaves down and put them in a pile. The "train track" is in a pile, too.
There were other random irises in my yard that I replanted a couple years ago, big fans but no blooms. I think I buried them too deep (at least a full inch.)
So this is my plan:
1) Till up a spot today and spray with roundup.
2) Wait until Thursday (my next day off) and plant the irises, just under the surface this time.
3) The spot is a sunny spot instead of shade.
Here are my questions:
1) Am I missing anything?
2) Is sun a good idea?
3) How far apart do I plant them?
4) Should I plant the "railroad track" sections that have roots on them? (I am assuming the ones with holes are no good).
5) Should I plant in clusters, in rows or what?
6) Does it matter which way the leaves face?
7) Should I trade some or plant them all?

IMHO, Full sun is best, 2 feet apart for best room, do NOT bury them completely, bearded iris need a portion of the big fat (sun root) exposed, doesnt really matter which way you point them as they will grow around anyway, clusters or rows is up to you. Dont be dismayed if they fail to bloom next year. If you feel overwhelmed when replanting, trade some for different plants.
charlotte

Charlotte gave good advice. I will pretty much echo hers.

1) Choose a spot with excellent natural drainage or build a raised planting bed. Bearded irises will rot with too much soil moisture. Amend as necessary to provide adequate nutrients and create a light, friable soil texture. Do not mulch directly over the tops of bearded iris rhizomes. Do not overwater.

2) Bearded irises perform best with full sun.

3) Planting distance depends on how frequently you want to divide your clumps. Planting at 2' spacings for taller medians and tall beardeds will generally allow 3-4 yrs growing time before division is necessary, though different cultivars can vary substantially in their rate of growth and expansion. In any event, you should provide enough breathing space between plants to allow for excellent air circulation to help keep iris foliage healthy and to prevent different irises from growing into each other and crowding one another out.

4) I assume what you are referring to as "railroad track" rhizomes are actually old mother rzs. Although they will never bloom again, they may still be able to grow new rhizomes (increases) from their sides if you replant them. Those increases will probably take 2-3 yrs to grow to blooming size. Many folks toss old mothers on the compost heap or in the garbage because they have so many mature, unbloomed rzs from the same clumps, they just don't want to waste the garden space and time on the mothers. If you have lots of garden space to fill and are willing to be patient for bloom, go ahead and replant them. If not, put them in a bag on your curb with a sign saying "FREE IRISES". They'll be gone by nightfall.

5) Plant however you want to plant. The aesthetics are up to you.

6) It's best to plant all the irises with the leaves facing the same direction because that'll tend to start all the clumps expanding in the same direction. Charlotte is correct, though, that after a year or two, the clumps will be growing in all directions, anyway.

7) Replant them all if you have the room and like the look of a mass of the same color irises. Trade some if you have more than you need or if you want some different irises.

You can find quite a bit more information about dividing and replanting irises and about causes of non-bloom in bearded irises on my website at:
http://www.angelfire.com/mn3/shadowood/irisfaq.html

Happy irising,

Laurie

Thank you both, and I bookmarked that site!