Is my spaniel EVER going to calm down?

Question
My cocker Honey just turned 3 years old.  I got her at about 9 weeks from a house enviroment where she wasn't given much attention and had become a little aggressive as a result.  To cure her of her aggression, I took her everywhere with me and introduced her to as many strangers as possible.  The posistive result is she is very friendly, the negative result is she HATES being alone.

Like most people, I work 8 hours a day and cannot be with Honey all of the time.  I have a huge backyard and she has a nice doghouse where she can relax.  She also has a large kennel in my kitchen where she sleeps, eats, or stays during inclement weather. (Despite the doghouse, I don't leave her outside if it's raining, etc.)  

When I come home from work, we go on a long, brisk walk.  She literally has an endless amount of energy, it seems no matter how much time I spend playing with her or exercising her, she is always unhappy (cries, whines, barks nonstop) if I try to leave the house.  Some nights she even howls at bedtime DESPITE me being home all evening with her.

My other issue with her, which sometimes seems related to her seperation anxiety and sometimes does not (she will leave a room I am in and go get into trouble) is that she is ENDLESSLY curious.  She wants to investigate (i.e. chew) everything.  No ammount of scolding seems to do the trick.  She has PLENTY of toys and chews to choose from but I can literally stop watching her for FIVE MINUTES and she will be in the bathroom, shredding toliet paper or in my bedroom chewing a shoe.

One solution I have considered is getting a second dog that could entertain her when I'm at work.  Do you think she would benefit from having another "member in her pack" to play with?  She is spayed and gets along extremely well with my parents' dog (another female) and pretty much any dog she's ever met.  OR is it more likely that she will teach her antics to the new member of the family?

Finally, should I stick with my current solution of keeping her out of trouble (never letting her out of my sight unless she is crated or in the yard) or is there a way to teach her NOT to chew?  She never has accidents in the house and was housebroken within a few weeks after I got her.  I've never had a dog with this issue before and it seems like she should have grown out of it by now, please help.

Answer
I hope your yard has a good fence and the gate is LOCKED.  Leaving her outside all day isn't a great solution.  And if she's crying/barking you'll have issues with neighbours.

What's happened here (very common) that to overcome one problem (which you did well), another one has been created.

First I'll say she's 3 - and will "probably" outgrow a lot of this in the coming year.  But scolding does nothing if there are no repercussions.  Same with kids.

So what to do?  Get a few empty pop cans..fill with about 15 pennies..duct tape top shut.
When you find her chewing - do NOT talk - pick up the can - say NO - and raise in air and bring down hard ONCE.  No chat - no scolding.  Just stand still and after she flees, go pick up the shoe/whatever.

Try that and let me know what she does.  Most dogs, after experiencing this once or twice will drop whatever they've got like it's on fire and just seeing you pick up the can will end the behavior.

A second dog will indeed copy the older dog.  So solve this issue first.  But yes, it'll add years to her life to have a companion.

And try to avoid the aggravation.  Put the toilet paper on top of the toilet - shut your closet door - put your shoes away.

I hate to tell you this but my 5 year old (who's a good boy) will still grab the end of toilet paper and race through the house with it :) and if I don't keep it out of reach I can come home to 40 yards strewn all over.

Now, as to teaching her to be alone.  You begin that when you're home and you confine her in the kitchen for 5 minutes.  If she "objects" - use the can of pennies.  NO - one loud noise - and walk away.  When she's been quiet for a few minutes, go let her out...no praise - no chat..just "let's go" as if you expect her to be calm.  Repeat and gradually increase time from a few minutes to longer.

I don't think she's really anxious - I think she's a bit spoiled (and mine, of course, aren't:)
so get on this and teach her what you expect.

Never yell - never scold.  The message is simple.  You do "that" and "this" happens!
Delores