Jalapeno--
About transposition--if a guitar-like instrument is tuned standard tuning, but a different key than the original, you really do not have to transpose all the time.
I am a guitar player, and have a Yamaha guitalele. It is tuned as it should be, a fourth higher than a guitar, with strings 1 and 6 tuned to A.
I do not transpose at all when I play it. When I put my fingers in the position I know if on guitar as an E chord, I still think of it as an E chord. (Although I know that it will actually sound like an A chord.)
For playing solo guitar, that makes no difference at all, that it sounds a fourth higher than what you call it. If it is to accompany singing, then of course you may have to play the song in a different key than you would with standard guitar tuning, to fit with your voice. (Which for some, might just mean using a capo.) If playing with other musicians, one will have to take the transposition into effect. (But I still think of that E chord fingering on the guitar as an E chord on the guitalele. I just play the song in a different key to fit with the voice or other musicians.
Think like a saxophone player. The same fingering is called C on all saxophones. However, that note sounds like a Bb on a tenor or soprano saxophone, and like an Eb on an alto or baritone saxophone. The player fingers the notes the same on all sizes, and thinks the same note name. However, unless he is only playing from notation all written out and transposed for him, he has to know how it will actually sound, that on no saxophone (other than the rare "C melody saxophone"), does the note actually sound the way you call it and think of it when you play.
To me the same in playing ukulele. Being a guitar player first, I did not learn ukulele chords. I just play guitar chords, missing the bottom two strings. And I still think of the chord with the guitar name, although I know like with the guitalele, that it sounds a fourth higher. (I would guess that a uke player who later goes to guitar might do the opposite, still think of an E chord as an A chord, think of adding two more strings to the uke chord, etc.)
I'd like to try the Cordoba Requinto 480, although I would not know what strings are best to use, and what is the best tuning. A standard requinto is more like the Cordoba Requinto 580. They are usually tuned a fourth up like a guitalele, but do do so use thinner requinto strings. With the smaller guitalele (or Cordoba guilele), due to the smaller size, one can tune tha thigh with regular classical guitar strings. The Cordoba Requinto 480 is in between those two sizes though, so not sure which tuning and strings would work best on it.
I don't know if the Cordoba Requinto 480 is still made though. It is listed on the Cordoba web site, but no online vendors have it in stock. An interesting in-between size though, between a guitalele size and the normal requinto size.