Are these rifles C&R?

Yes

I'm thinking about picking one up. How accurate a shooter are they ?

I have one.  Pretty good shooter.  These things kick like a mule.  They do have a few quirks.  On mine the cleaning rod tends to walk out when I fire it.  You have to have the cleaning rod in becasue it holds the front barrel band in place.  

Many people who load their own like to cut back on the powder a bit.  There is a long argument about whether the receiver metal is soft or not.  Mine is fine.  I just check the head space once in awhile.  Many people use them a brush rifles.

what would you define as a brush rifle?  just curious, heard this term used a lot.

 Brush Gun:  any rifle you would carry with you into the woods, that if scratched, bashed, lost, broke or otherwise molested will NOT cause you to weep like a small child.

 Often a Brush Gun is a 94 Winchester, that belonged to every other male in your extended family
or an Enfield/Nagant/SKS you picked up from a guy that owed you $50.00.

Synonym: Truck Gun

Useful firearm with little monetary or emotional value

 ALSO:  owned two of these rifles in the 70s/80s  DO NOT fire commercial .308 ammo out of this rifle, DO NOT fire Indian 7.62 or any 7.62 NATO Rounds sold as "Machine Gun" ammo out of this rifle.

 This is a 96 style Mauser action and you should stick with the lightest bullet weight you can get in 7.62 NATO Milsurp Ammo.  There are those who will tell you this rifle is unsafe, prudence and perhaps blind luck on my part did not prove this to be so.  Be your own judge.  They are accurate, and I did not find the recoil overly stiff with Milsurp ammo.

I have a Guardia Civil Spanish Mauser and I think the firing pin is broken because it does not fire...
It doesn't even leave a mark on the primer. Has anyone had a problem like this?
I have to admit, I am a bit cautious about this rifle, as noted above and on every other website that discusses this rifle as being made from inferior steel and with less lugs than the 98 models.

Just saw a nice one at shp in my area for $139. The issue concerning the steel is one that I have also heard for years. If I were to shoot one I would stay to the low pressure loads just in case.
Didn't Guns & Ammo run an article on this a few years back?

http://www.geocities.com/fritz125541/Gammo

This is the link to the Article, read for yourself.

The old wives tale about Spanish soft steel has it's roots in the knockoff handguns made in the Basque region from the early 1900s to 1950s or so.

The concerns with the 1916s deals with the way the action deals with gases if a primer is ruptured and the amount of stress the small ring 93 style Mauser action can handle.

 Always ask the critics for the details on one of these rifles blowing up as a result of shooting Milsurp 7.62 ammo.  There is one "alleged" case complete with photos around but the shooter was
shooting reloads.  I find it hard to believe any company  would sell these rifles for 30 plus years and remain in business if they became bombs regularly.

 REMINDER THERE IS A DIFFERENCE IN 7.62 NATO AMMO AND COMMERCIAL .308 WINCHESTER AMMO, and loading for these rifles at 7x57level (47-49, 000 CUP) can do you no harm and will make you feel better.

As stated above,  a brush gun is usually a beater, but also short and easy to use when traipsing through brush or woods.   Sturdy and reliable too.  A Mosin_Nagant 91/30 is cheap, reliable and long.  Not a good brush gun.  A Mosin Nagant M38, M44 or M91/59 is cheap and short.  A good brush gun.  To me a brush gun should also be able to bring down just about anything you encounter.  

 I have an excellent M-38, no way does it get the treatment my Indian phony Jungle Carbine in 7.62 NATO does and that is my current "Brush Gun".

 Besides the muzzle flash from my M-38 is a forrest fire hazard.  7.62X54 is marginally better than NATO  7.62 unless you reload 7.62x54, I don't think there is that much difference, however when it comes to being sturdy the Moisin Nagant has it all the way