#1
I was thinking that in the near future instead of a new guitar I might just spif it up a little bit Im currently using an epiphone les pual custom vintage flame Burst (black to brown) and I want to put a gold bigsby on it and seymore duncan pearly gates(neck) and a seymore duncan cust custom (bridge) i was wondering if a bigsby changes the sound of your guitar any? Better or worse? Whats the average price? I saw them on ebay but the prices kinda seemed way up and way low
" Im so god damned horny the crack of dawn better be carefull around me."
- Tom Waits

Gear
Marshall Jcm900 50w Head
Epiphone Les Paul Custom
Fender MIM Telecaster w/ rosewood neck&Emg's
EHX Holy Grail
Tone Bone Hot British
#2
Shouldn't change your sound noticeably at all because its mounted directly onto the top of your guitar's body and no wood is removed for cavities and such (unlike Floyd Rose).

It depends on how much you like your guitar. If you're going to upgrade it to another guitar any time soon then it's not worth it, but if it's your main axe and you love it then the pickups will be a good upgrade, and Bigsby's are, from what I've heard, reliable non-locking trems.

If you can afford the upgrades just remember you'll need to pay someone to fit them for you, unless you can trust your hand at some woodwork and electronics!
Gear:

Gibson Les Paul Custom (Ebony)
USA Jackson KV2 Sunburst
Jackson KE7
BC Rich NJ Classic Mockingbird

Marshall JVM410H
Marshall 1960A

Korg Pitchblack
MXR Super Comp
Dunlop Slash Wah
ISP Decimator