My parents in OK make beef jerky, fudge, peanut brittle, etc. I
would like to set them up with a website to sell and ship it,
primarily only for a modest profit for out-of-state friends &
acquaintances (who have sampled the wares and beg/extort me to bring
them back much more when I go to visit).

I need someone to research the legality of this, and explain what
steps (and at what volumes & types of sales) would need to be taken to
start and possibly even scale up a very small operation like this. Eg,
is it ok to sell stuff to friends as long as I don't sell more than a
certain amount, or advertise a certain way? Is it ok to sell certain
things, but not others? Can they only be mailed a certain way?

NB - I am fairly certain setting up & maintaining a licensed
commercial kitchen would be out of the range of this project.

If you need more local information (county etc) before considering
research, you can contact me!

Thanks

I initially began answering this, and then re-read the products that
your parents are making -- beef jerky, fudge, and the like.  I'm now
sufficiently uncertain of my information that I'm just going to add
this research as a "comment," for whatever it's worth.

Oklahoma does in fact regulate both food "manufacturers" and food
"retailers."  I believe that your parents' operation, selling packaged
food ready to eat, places them in the category of "retailers," which
are "food service establishments."

"'Food service establishment' means an operation that stores, prepares,
packages, serves, vends, or otherwise provides food for human consumption
or any establishment that relinquishes possession of food to a consumer
directly, or indirectly through a delivery service."
http://www.health.state.ok.us/PROGRAM/cpd/256.pdf
(scroll down through the definitions) 

There is a list of exemptions to the licensing requirement.  The only
possible exemption that appears to apply to your parents is:
"a kitchen in a private home if only food that is not potentially
hazardous is prepared for sale or service at a function such as a
religious or charitable organization?s bake sale..."
http://www.health.state.ok.us/PROGRAM/cpd/256.pdf
(scroll down to Page 12)

And this is where I got concerned about the specific products your
parents make.  Beef jerky, being a meat product, doesn't fit the "food
that is not potentially hazardous" category.  Neither does fudge,
since I think it has eggs in it.  "Food that is potentially hazardous"
is defined in the regulations, and it is essentially anything that
will spoil and make people sick.

So.  If your parents intend to do this, they do appear to need a
license.  But all is not lost!  Licensing is not all that difficult,
according to other home-based cooking entrepreneurs:

http://businessownersideacafe.com/business_ideas/business_home_baking_cd1.html?IC=cba01e4ba9466272417bb993ba7666f8

http://www.motherearthnews.com/library/1983_January_February/At_Home_in_the_Baking_Business

http://home.ivillage.com/homekeeping/homefinance/0,,nzcz,00.html

There are also lots of books available, such as:
From Kitchen to Market (From Kitchen to Market: Selling Your Gourmet
Food Specialty) (Paperback)
by Stephen F. Hall
http://www.amazon.com/gp/product/customer-reviews/1574101382/ref=cm_cr_dp_pt/104-0182895-5210326?%5Fencoding=UTF8&n=283155&s=books

Anyway, I'm sorry I couldn't be more definitive, which is why this is
a comment and not an official "Answer."  Best of luck!