We've been using using Irish Spring as a deterrent the for past few years with great success.
I can't guarantee it will work for everyone (or every species...we primarily have deer and rabbits), but I can say that when we've had hostas and DIDN'T use the soap we went to bed with beautiful foliage, and woke up to lonely leaf stems.
Head to the supermarket and buy a 12-pack of soap.

We have a lot of yard, a lot of deer, and a few nice neighbors to share with, so I usually purchase three big packs and make extra.

Take out your food processor and using the shredder attachment....

...shred some 'Spring.
Then, spread some 'Spring around your garden!

The strong scent wards off critters and has protected our plants. Refresh with a new sprinkling every two to three weeks or after a heavy rain.

One 12-pack loosely fills my processor bowl three times.
How far it goes depends on the size of your garden and how liberally you spread it. We apply it as shown above, then just add a little more on occasion to freshen the scent.

(FYI: You might want to break out the vinegar to aid in cleaning up your food processor. No one wants soapy tasting cranberry-orange relish at Thanksgiving!)
REGARDING THE SOAP/SOIL QUESTIONS:
I called a local cooperative extension to clarify.
The helpful person noted that she also uses soap to protect her own plants with success...but thought that "excessive" use over a period of 10 years might have some effect. She did not think it was harmful to the plants.
REGARDING RABBITS, GROUNDHOGS, MICE, ELK, SKUNKS, SLUGS, LIZARDS ETC:
WOW! Ya'll have some variety of wildlife :) I'm sorry that some of your questions were beyond my experience. I didn't answer at first hoping that someone with additional experience or info might jump in (and thank you to those who did)...so sorry if anyone thought I was ignoring them. All I can say is we've been thrilled with this remedy where we've used it...and by many of the supportive comments, so have a lot of you. Happy Gardening!