You have asked a lot of questions without giving us very much information to help you. Please take photos of all the different trees and post them here.
If there is any way to contact the previous owner and ask about varieties, rootstocks, ages, etc. that would also help .

There are a lot of knowledgeable folks here who can and will help you.

Regarding ID... the shape, size, leaf petiole, things like that can differentiate between lemons, grapefruits, oranges, others

Sounds like you have a variety, maybe pruned to fit a landscape... you can prune citrus easily for shape... topiary, espalier, hedge, even bonzai.

Water them, give them a well balanced citrus fert 3-4 times per year and wait to enjoy whatever you have inherited.

Sorry I don't own a camera, but I managed to get these two pics of the thorny tree. Do these links work?

https://picasaweb.google.com/heather.leigh.green/May272012#5747279401378673074

https://picasaweb.google.com/heather.leigh.green/May272012#5747279453252197026

This is the thorny citrus. One pic is to show the shape. It's similar to all the weirdly shaped trees. The other it to show the branch that grew out with different shaped leaves. I'm holding one of the normal branches with the little oval leaves next to the branch with the large soft pointy leaves.

Those links don't work...

https://picasaweb.google.com/heather.leigh.green/May272012#5747279401378673074

https://picasaweb.google.com/heather.leigh.green/May272012#5747279453252197026

Sorry, I've never used Picasa before. I think I had it set to private. I just changed it to public. Thank you for your patience.

Citrus are bushes:)

Okay, all the branches with trifoliate (3-leaf clusters) leaves are suckers from the root; cut them off where they come out of the trunk, or below ground; water and fertilize what is left and you should be able to save the "real" tree, which looks to be some sort of lemon.

I understand citrus trees can be shaped as trees or shrubs, but I want mine to be like trees. I have a 20 foot tangelo tree and it's offers lovely shade. Is there a way to make this tree do that too.

As for suckers, the part with the big leaves is the sucker, right? It's only one branch.

Thank you for your help

K. I cut off the sucker. It was actually part of a trunk. All the other branches looked more like suckers... Hopefully I did the right thing. It was only two little branches, so it would be weird if the other parts were the sucker I think. It would make the sucker the actual tree and that would be strange I think. Hopefully I didn't do damage :(

I was able to take pictures of the other trees with my cell phone!

Ok, so here we have what I am almost positive is a lemon tree:
https://picasaweb.google.com/heather.leigh.green/May27201202#5747330872321811346

This is the tree that had one lemon last year, though I never tasted the fruit- but it looked like a lemon.

This tree also has very bad leaf curl. Here is a pic:

https://picasaweb.google.com/heather.leigh.green/May27201202#5747330975224339442

I think this was from being really thirsty last summer. I water deeply about once a week, but it doesn't seem to get much new growth and the leaves don't change. Should I do something else?

Next pic:

https://picasaweb.google.com/heather.leigh.green/May27201202#5747330981373239506

I don't know if this is lemon or lime and the shape of the tree is terrible. Is there anything I can do to fix it and get it to look more like a shade tree eventually? Here is a pic of it's baby fruit as well:

https://picasaweb.google.com/heather.leigh.green/May27201202#5747330979421196178

Next pic:

https://picasaweb.google.com/heather.leigh.green/May27201202#5747330997258299090

I don't know what this tree is.

Here is the fruit pic:

https://picasaweb.google.com/heather.leigh.green/May27201202#5747331006607107522

Same question about shaping the tree from above.

This next tree is only about 3 feet tall, it has horrible thorns like the first tree I told you all about. I'm not sure if I should dig it up and plant shadier trees or if it's worth preserving. I love fresh fruit.

https://picasaweb.google.com/heather.leigh.green/May27201202#5747331013173657138

This is another mystery citrus tree. I have ever seen fruit on it.

https://picasaweb.google.com/heather.leigh.green/May27201202#5747331020964139874

Same question about the shape.

Thank you for your help!!! I am very overwhelmed. I haven't even began to tell you about the ash trees and the apple tree... but this is the citrus forum :)

Looks like someone had cut them too short at one time. Is it all suckers?

I don't think so. They have fruit on them, but they do look weird. Do you think they are all suckers? Shoot, that would suck.

If I were you, I think I would probably take them all out and start again with good quality trees that you know what they are. As for shade trees, if you buy your trees on a sour orange root, like Carrizo, or on Macrophylla, they will grow to full size; if you buy them on dwarf rootstock, like Flying Dragon (What Four Winds uses); they will grow slower and remain smaller.

I think in the original fotos you submitted, there were only about 2 branches of the "real tree"; if you cut them off you are left with Trifoliate, which is basically worthless, except as a rootstock for grafting.

A couple of the other fotos look like all suckers (Trifoliate); but the one with the green fruit with the nipple-like end is probably a Lisbon lemon (could be Eureka); it might be worth saving, but again, if you are looking for a larger tree and the existing trees are on a dwarf rootstock, you are never going to get there. With water, lemon, and sugar, you are NEVER going to get orangeade.

3 of them have fruit. And the first one had one piece of fruit, but it dried and popped off.Do suckers get fruit?

So I think you all were right. The first tree was trifolate- sad. I chopped all the suckers off and all thats left is a stump. I'm going to dig it up tomorrow and see if I can buy another fruit tree at Home Depot tomorrow. Also, the tiny tree was also a Trifolate, but the others I think are lemon trees. The ones that I took a picture of their fruit. Can anyone confirm that? I can take a better pic of the leaves.

If the growth is growing above the graft its probably good scion wood. If its below then its rootstock.

If its nothing but rootstock, I think sometimes they can grow fruit but the fruit will always be of the rootstock and usually sub par or sour. I am unsure if all rootstock can grow fruit. I really dont know.

But you might have ALOT of suckers and one or two good scion wood growing. IF so just cut off all the suckers below the graft.

Also you can still use that tree/rootstock (stump) to graft as many different (or just one) citrus that you want. Personally I would keep it to practice grafting.

I dont know about the lemons:-)