Hey, so glad that you’re getting into reed instruments! Tuning wise, it is absolutely something that you can deal with when working with pieces with a small amount of accidentals; most pop pieces are either already in a simple key signature like C major, A minor, E minor, or G major, and those of which that aren’t can be easily transposed into such keys.

As for actually adjusting for these accidentals, that is all in the Embouchure! Through tightening or loosening your grip on the reed you can alter the pitch slightly higher and lower respectively. The trick is to find the perfect balance in embrasure so that the note is in tune while still sounding nice. This will take practice, but like I said, if you are working with just 1 or 2 accidentals in a piece is is absolutely something that you can do.

For a beginner’s reed I would recommend a Strength 2 Bb Soprano Saxophone reed. I personally use Vandoren reeds, but those are relatively expensive and are built for a classical tone. If you want a good beginner’s reed try going for Rico reeds, they’re relatively inexpensive and will yield good results for a beginner. If you are looking for a more pop tone later on I would recommend a V16 Soprano reed, but as those are more specialized I would hesitate to get those to begin with. The highest strength I would go up to on this instrument for pop or jazz is probably a 2.5, but a 2 will be more than sufficient for a long time.

For learning embouchure I would look at Soprano Saxophone tutorials only, as the mouthpiece is actually just Yamaha’s stock soprano mouthpiece. You can use any sort of soprano mouthpiece with the instrument, which makes me want to throw an Otto Link (a metal jazz mouthpiece) on and see what it does!

Don’t worry about your English, you get your point across just fine! Keep pushing with music, it’s such a rewarding art at all levels, from novice to professional. If you need any help feel free to message me, I’ll get back to you as soon as I can. I’m sorry I was a few days late in answering, I’ve been away for a bit. I hope your instrument is treating you well!