You can trust yourself to a teacher, as many do- but in the end only you can really come to closure on these questions.
On size does not fit all. Each learns as best matches their nature.
That said, "It's always best to start at the beginning." Bypassing things before you've mastered them usually results in slipshod mastery; you're in essence discarding the method you intended to follow. The memorize or sight read question is more individual. I always try to sight read, and when I can't I then grind at whatever it is that I can't until I can. Is that memorization? Surely in large part.
Though "guilty as charged" I generally disliked playing a piece that I'd beaten into submission through massive practice preferring to take smaller sequential steps in expanding my skill set. That does not at all mean that when I encounter a piece I can sight read and I enjoy I do not play it again and again and again to wear off the rough edges, then refine the interpretation, and then be able to toss it off freely with such embellishments as I may desire based upon a whim of the moment.
Those who intend to play for an audience- for love or money or a combination of the two (probably the preponderance of musicians) will surely wish to memorize the pieces thay intend to present.
By and large if it's simply too complex for me to sight read coherently (sight read quite slowly still counts as coherent to me) I seek out something that is still too difficult to sight read, but by a smaller margin- in that grey area where I can just barely do it comes the most improvement.. I pick and choose pieces these days rather than following a method and though I started out plouging through Palmer Hughes I pretty much always supplemented the method book with a wide array of music. Largely I play what pleases me.
"Who do I make happy with this self centered approach- for I play to no audience but me-?"
"Me."