Is this proof of Perron's theorem correct, and if so is it original?
(1) Correctness: I read all arguments in detail and couldn't find anything wrong with them. Of course, this doesn't mean too much...
(2) Orginality: I think in a topic which has such an extensive historical record as Perron-Frobenius theory does, the question of "originality" or "novelty" of any particular proof is a very delicate one.
There is an enormous amount of literature out there which all deals with spectral properties of positive matrices in one way or another. I recommend to have a look at MacCluer's survey article [MacCluer: The Many Proofs and Applications of Perron’s Theorem, 2000, SIAM Review, Vol. 42, No. 3, pp. 487–498] for an overview over some proofs of Perron's theorem and for references pointing to several further proofs.
But even if somebody had an overview over all the relevant literature and could thus decide with sufficiently high probability whether the OP's proof (or a very similar one) is written somewhere in the literature, we would still face the problem that, even if the proof as a whole was new, this does not necessarily mean that any of the single arguments in the proof is new.
In fact, in addition to all the articles and textbooks with proofs of Perron's theorem, there have been extensive (and successful) attempts to generalise Perron-Frobenius theory in various directions (for instance, to matrices which leave invariant a cone in $\mathbb{R}^n$, to eventually positive matrices, to Krein-Rutman type theorems on ordered Banach spaces whose cone has non-empty interior, and to Perron-Frobenius theory for positive operators on Banach lattices, in order to mention just four of them), and many arguments used in those theories are variations of techniques from the classical theory.
Hence, it is quite save to say that, for any argument used in any "new" proof of Perron's theorem, we can find a similar argument somewhere in the related literature. Here are a few examples to back up this claim (in the following, I assume for simplicity that the spectral radius equals $1$; this is no loss of generality since we can replace $A$ with $A/\rho$):
The second bullet point in the question essentially says that, for every eigenvector $\psi$ belonging to a unimodular eigenvalue, the modulus $|\psi|$ is a super-fixed point of $A$. This observation is essential for many arguments in Perron-Frobenius theory on Banach lattices (see for instance [Schaefer: Banach Lattices and Positive Operators, 1974, Springer, Proposition V.4.6])
The argument in the third bullet point in the question is for instance used in [Karlin, Positive Operators, 1959, Lemma 3 and Theorem 8 on page 921]. In the subsequent corollary, Karlin uses this argument in the same way as the OP to deduce the same result (on infinite-dimensional spaces, though).
The argument in the seventh bullet point in the question (which shows that the spectral radius is a geometrically simple eigenvalue and which is attributed to Wielandt by the OP) can for instance be found in [Karlin, op. cit., Theorem 9 on p. 922], where the argument is in turn attributed to Krein and Rutman (but I don't know who was earlier).
The OP's subsequent argument (which proves algebraic simplicity) actually shows the following general spectral theoretic observation (which is independent of any positivity assumptions): If $\lambda$ is a geometrically simple eigenvalue of a matrix $A$ and if there exists an eigenvector $\Psi$ and a dual eigenvector $\Pi$ such that $\Pi\Psi \not= 0$, then $\lambda$ is also algebraically simple (positivity of $A$ is only used to show the existence of such $\Psi$ and $\Pi$ and to deduce the geometric simplicity).
[Actually, I wasn't aware of this spectral theoretic fact, and the question brought this to my attention - so let me express my gratitude to the OP for that.] I do not know any place in the literature where this can be found, but it seems very likely that this is known. Maybe somebody else can help out with a reference here?
Of course, one could argue that most proofs published (even of new results) are just a recombination of known arguments from various branches in mathematics, but here we have the very special situation that the known arguments which are combined all stem from essentially one field, namely from the spectral theory of positive matrices and its generalisations - and that they were all used in the literature to prove results which are very closely related to the already known theorem under consideration.
Thus, I would argue that one should rather not consider the OP's proof to be really "novel", even if it might not be written down explicitly in the literature.
Those things said, I feel obliged to add the following three points:
It is certainly rewarding, though, to seek for versions and variations of proofs of Perron's theorem. A proof which efficiently combines a few elegant arguments - as the OP's proof definitely does - can be very helpful in teaching (and after all, that's where the proof under discussion comes from, if I understood the OP correctly)
I personally find the OP's version of the proof quite appealing. It's very clear and easy to follow.
Concerning your motivation to "feel proud of yourself": well, you certainly should feel proud of yourself - you found that proof, and a good one at that.
As someone who lives and dies by the Perron-Frobenius theorem (PFT) and who is familiar with a good deal of the literature on nonnegative matrices (and generalizations of nonnegative matrices), your proof is, to the best of my knowledge, original and correct.
IMHO, the demonstration is worthwhile because it is accessible to advanced undergraduate students who have taken a second course in linear algebra and because positivity is instrumental in the demonstration (contrast with the proof of the PFT via the Brouwer fixed-point theorem, which is quite elegant but many students at the undergraduate level will not have exposure to it). Even though, as Jochen thoroughly notes in his response, your proof (unintentionally) draws on ideas from other proofs, your demonstration pulls these ideas together in a very accessible way, which is the novelty.
Given the above, I think you should consider submitting a carefully revised version of what you posted to the The American Mathematical Monthly or The College Mathematics Journal as a note — if it is not successful those journals, then you can certainly try some research journals (e.g., Positivity or the linear algebra journals ELA, LAA, and LaMA).