hey, I've been using a tremolo technique by pressing down the strings between the fretboard and the tuners, just about at the start of the headstock, because i dont have a whammy bar, so anyways just wondering could the sudden increase in tension on the wrong place of the guitar damage it
nah It's perfectly normal, but its mostly used for bending or vibratoing open strings. I think, other than open strings you should use your actual fretting fingers to bend and vibrato much easier and more economic.
No; Jimmy Page famously used that technique during the Heartbreaker solo.

Further, that's not exactly a replacement for a trem as a trem is more for lowering pitch than raising it.
Quote by DeathByDestroyr
What the hell is a G&L.

Quote by Flux'D
Gay & Lesbian I think, the box smelled funny
Greg what did you send me??
Yeah lots of country players do this.....Johnny Hiland's PRS Signature model actually has a recessed trussrod cover so you can perform whole tone bends behind the nut...