OMG.. where is the bad advice image when you need it!!!
cherokee6 is dead on with his book recommendations, but the rest Id be weary of trusting.
both the Tele and Strats use the 25.5 scale(at least the 2 I have)
both of mine use a rosewood fretboard on maple, and my Tele is right handed(but I play left handed)
what do you mean you want a left handed neck? necks are universal, its the nut and body that are the biggest differences, mostly with the tremolo bar(or standard bridge) and the knobs. So when you design with plans, yes you simply flip them. But a neck really isnt different but for the tuner locations and how the nut is cut.
I highly doubt the 24.75(gibsonish, theres so many different ones) 25(PRS) and 25.5(fender standard) play a HUGE difference in tone, if even at all.
Id say the wood and build have more to do with that. As well as the pickups used of course.
the "LP" sound compared to a "Strat" sound has alot to do with the LP being a set neck, Made of Mahogany(EVEN THE NECK), using a TOM bridge, double humbuckers, or a ebony or rosewood fretboard. While the strat uses a alder(or poplar, or basswood) body, usually a maple neck with a rosewood(or just maple) fretboard and of course the single coil pickups.
to get a "strat" sound out of my tele, I think I would change the bridge and neck pickups to something a bit warmer, (look at Seymour Duncans stuff) up the guage of the strings to 10's or 11's and maybe even change the bridge(although I doubt it has to much of a effect VS. a hardtail strat)
but for you, Id READ READ READ READ..
Id buy Melvyns book, Make your own electric guitar.. Id say its the starting point for almost everyone off this board who takes pride in their work. Read it twice. Then go to the guitar store, and actually LOOK at what makes the guitar works after you read the book and understand. then you can start worrying about the tone, and sound, and resonance, and whatever voodoo you want to believe in.