I have had no problems with mine.  In short I love it and would recommend it.

http://www.amazon.com/gp/product/B008FLYROG/ref=oh_details_o00_s00_i01

I've used a "shoulder bag" for years and never liked any of them.  Now I need one worse than ever to carry my gear, including wallet, phone, camera, tablet and a few accessories.  I want one just big enough to get me by.  I found a very nice one here http://www.sfbags.com/products/muzetto/muzetto.php that costs almost as much as my Nexus.  I'm willing to spend some money to get something I like, but I'd like some options before I drop some big bucks on this.

I poked around Amazon and Google agonizing over which case to buy.  I really hated holding my bare naked N7.  I'm grateful I didn't drop it before buying a case.  I finally pulled the trigger on the Moko Slim-fit just because it was the last one I looked at and had very good user reviews.  No doubt I will add mine.  I'm very happy with it.  It holds my tablet snugly, turns it on and off and generally feels great.  All for about $15.

No, but the tech support person seemed to indicate the volume setting could be different for the speaker jack than through the on board speakers, including the mute. 
Either that or the external speakers/headphone require a higher volume setting to be heard.   

This comes under the heading of "boy do I feel stupid".  I just got off the phone with Nexus tech support.  The problem was not that the jack was not working, but that when you switch from speakers to headphones or external speakers the volume controls change.  I guess there are separate controls depending on how you are listening.  So after being advised to, I turned up the volume and yes I could hear.  Besides feeling "stupid" I also felt happy since Walmart's return policy on tablets is only 15 days.

So happy ending.  Now, on to bigger and better things.

So far just Overdrive and Kindle App which fit most of my public library needs.  The idea of checking books out electronically has me giddy.  Nothing to lug around, no library fines.  Even better I don't have to think about which books to take with me.  Except for the tablet, they are all weightless.  I feel very cool and proud.  ;^)

Any tips on how I can backup and restore my data, apps and profile when I get a new one?

This is my first tablet ever.  Problem number 1 in entering text.  I love to type and can do so quickly enough to converse this way, but not on a tablet.  I am resorting to my desktop right now so I can say what I want without thinking about it.  We I use my Nexus I spend more time correcting and editing than I do writing.  I'll get over it, but it is a hurdle.

I've have my Nexus just over a month.  I like all the apps and internet related features, but depending on wifi is frustrating.  I got used to my smartphone (which I don't currently have) and as often as not I can't use my favorite apps.  Even at home my wifi connection is not very robust.  I can't blame this just on the nexus, but still.  It is enough of a problem that it limits my use.  I chose the nexus as an affordable alternative to a 3G or 4G device.  I made my bargain and I can live with, but next time around I'll think twice.

I like the Jellybean OS.  Much better than my old Droid 2. whatever.  I've lived in a Windows world so long I still miss simple things like a tab key, delete key or a few basic function keys.  I'm old, but I'm adapting.  Given time, I'll be good at it.

Just as I'm getting used to and fond of this thing I might have to return or replace it.  My headphone jack has stopped working and this annoys me to no end.  I've come all this way and installed all these apps and now I'll have to take it back and get a new one.  I'm finding myself concerned about the quality of the product.  What might break next.  I'm wondering if this is the best place to put my money, not to mention my time.

Wish I had a happier tale, but I'm not looking forward to setting up my tablet from scratch.  My next stop will probably be Walmart to try to get a replacement.