Need lots of help!

I just purchased a house last month. There are quite large flower gardens. The problem is I am clueless. I have never tended to plants or flowers. Friends and family are trying to help me out and I am so willing to take this all on I just don't know what to do with some of these plants. So to start here are a few of my ??? ( I am sure there will be more to come!)

I have six beautiful peonies. They have already bloomed and seem to be done. Now where the blooms were are 3 what look like pods. Do I cut these off? And if so how far down do I cut them?

I also have lots of columbine scattered around. Do I cut off where the blooms were on these? I would like to group them together do I wait till fall?

And for now my last question will be for irises. Do I cut off where the blooms were? Also how far down do I cut them? Can I split them? When is the best time to do so? The section of garden they are in is full probably about 2ft X 5ft.

Oh wait one more. i have a ton of Snapdragons, everyone tells me that they are annuals is this the case? If not can they be transplanted or should I not count on them coming back next year?

I have others and I will be posting some pics of ones I have not identified with hopes that someone can.

I live in Michigan. Any help would be greatly appreciated. Also if you could please put any advise in laymans term it would be appreciated, because I really am completely new to all of this.

Thank you in advance.

Iris look more tidy if you cut the bloom stalks as far back as you can.
As far as dividing them, yes, if the rhizomes are putting on 'babies' you can separate and plant each rhizome. Don't bury them! They will rot. Just put them halfway into the soil with the top showing.
If you do divide the iris, if you want you can cut half of each leaf off. That way the plants will be less likely to topple over until they establish new roots to hold them in place.

The snapdragons may return from seed that they have dropped. You will know next year when the time comes for the seed to sprout. I am in Texas, so I have no idea when that might be in Michigan.

As for the peonies, unless you want to try growing from seed, I'd cut off the old stalks just for asthetics, down to under the foliage. Most garden peonies are sterile anyway. If you don't want the columbine to reseed, cut off the stalks. (This won't make them rebloom though.) I've had good luck relocating mine in the summer, as long as you dig up the whole rootball and water well.

Last year was my first year for snapdraggons. Even though I deadheaded quite a bit I still ended up with a bumper crop of snapdraggons this year from last years reseeding. Just have to know what to look for. I started noticing mine at the end of April. I let them get medium sized before I dug them up and moved them about.

I try to wait and do all my plant moving in the fall (mid-end Sept). The plants seem to rebound better. That said, I did move some Black eyed Susan and Gaillardia last year in the beginning of August. The plants did make and and look fine this year but they looked really bad last year!

Have fun!
Jennifer