Two-Part software/hardware question for new rMBP and first time Mac owner

I'm glad to have learned that there is a professional forum like this to address noob Mac user inquiries.

I am a police officer and have just purchased a department rMBP to utilize in conjunction with evidence custodian responsibilities. I'm pretty computer savvy and the transition from previous windows based products has been a smooth experience thus far.

Ironically, I'm the guinee pig for the department and will be passing operating knowledge onto fellow cohorts here.

First, I'm looking for advice on locating a non-complex secure file shredder program. I'm certain there could be some freeware versions out there, but a licensed product would be fine also.

The second part of this inquiry, with the absence of the optical drive on the rMBP, we will obviously be utilizing the SD and/or USB port for importing photo data... Could someone recommend a reliable external hard drive for backup? Ie; notable/tested manufacturer.

My last question, once installed with the selected file shredder software... Will this software be capable of disposing selected data directly from the external hard drive while connected? Or does the data need to be first transferred back into the main CPU memory to be discarded?

I appreciate the support.

Regards,

Ken

P.S. Our rMBP is the base $2199.00 15" model.

Look no further than the Finder.

Trash whatever it is you want to shred - open Finder - in the Finder menu you'll find 'Secure Empty Trash'.
I believe that does a 35 pass overwrite which is overkill for pretty much everything.

For more - link.

edit:
Anything put unto the trash from the external - yes, the external will need to be connected to securely erase.

I have had great luck with Western Digital drives (Studio)

That's fantastic...

I'm looking at it now, and that's really easy. Surprisingly, that feature regarding the finder/shredder capability was not covered by my pimpled sales associate. Glad I asked before spending more taxpayers money! ;-)

Thanks for the assistance gentlemen.

If you're in the market for a good OS X bible - try this one out - link.