Questions About Black Cats, Genetics and Feral Cats

We currently have two house cats that have no specific lineage... they
are just your ordinary run of the mill mongrel cats. We love them both
as if they were our own children (well, almost, hahahaha). Over the
course of this winter whenever it snowed I noticed tracks leading to
and from a hot tub on our deck. The hot tub has a door that leads to
the inside where all the electrical connections are but the hot tub is
not hooked up to electricity at this point in time (and it has
provided shelter for birds and other wild life in the past). The door
has been slightly open to the inside of this hot tub. Never the less,
it became increasingly clear to me over the course of this winter that
some creature was living inside the hot tub.

The creature turned out to be a black cat. I cannot recall
specifically when I first saw this cat hanging around. I think it has
been at the very least a year or two, maybe three years or more. I
simply was not paying attention since we have a few neighbors who let
their cats run and we see those cats from day to day, in addition to
the usual number of stray and feral cats.

Long story short, I do recall seeing a black cat around here. I simply
assumed it belonged to someone in the area. He/she is very shy...
never one to approach. I do recall this cat hissing at me once in the
dark, but I cannot even recall the specifics.

After watching this cat for awhile... watching the tracks, feeding him/
her, I finally got around to live trapping it. The cat is currently in
our pole barn "under quarantine". I don't dare bring the cat into my
house at this time since I would never want to expose my two indoor
babies to any communicable diseases.

The live trapping was predictable... the cat was really fearful. He/
she came around the second or third day on quarantine. The second day
the cat was still hissing at me so I fed and watered him/her, but did
not attempt to pet the kitty. On the third day we got to know one
another and I was surprised that he/she was so receptive to attention!
WOW! The cat is rolling all over the place and loving the petting and
love!

At this time I am allowing the cat outside of the cage under
supervision - meaning whenever I am out working the cat is out, too.
He/she hovers around the cage, shyly... but I think I will keep
encouraging him/her to get as comfortable inside the cage as outside
the cage. And I know... this is a cat that has fended for itself for a
very long time... lol

I am not sure I need a barn cat, but I am equally not sure if this cat
will adjust well to being an indoor cat, though I believe he/she will
eventually.

I am not really even sure how to sex a cat. It is hard to tell. This
is either a neutered male or a female... and since we have not seen
kittens around here, and I am not seeing any signs of pregnancy, I
don't dare guess - I suspect this cat has already been neutered but I
don't dare guess.

I have also noticed that this is an all black cat... truthfully, it is
the "blackest" cat I have ever seen... but in good light I can see
that he/she is really a very dark, dark brown. I do not see any other
color pigment. I always thought ALL black cats have some white on
them. Is this a myth? I don't even see any white guard hairs! I didn't
know ALL black cats existed!

Can anyone tell me (or help) if a feral cat can ever make a good house
pet? I am beginning to strongly suspect that at some point in time
this cat has had some experience with humans and is not truly feral.

Is there such a thing as a "true" black cat?

Any responses will be very much appreciated.

Thanks :-)