Original yes
Replica you can get even 14"

Depend on colour/model/fitment
You need to check with a reseller
I guess from 4k 5k to 1xK for wide wide fitment Meister S1 3 Piece

Klang is famous for cheaper tyre/rim and they accept trade in
Usually,get my car tyre change at T3 Auto Service
If you intend to trade in rim and want to have wide selection,Klang is good place
I dunno the name but i visited once,it's an industrial lot and they have wide rim selection

Your stock size is 205/55/16 or 225/45/17
You can go for spec similar to SLK55 AMG which is 7.5Jx18 front 8.5Jx18 rear with 225/40/18 and 245/35/18(Rolling diameter is similar to stock)
One more thing to take note is you need to buy wheel with 5x112 PCD(Same with VAG car)
Picture of my friend's setup(which i think looks good):

I know back tyre size is 255/35/18
Try to hunt for wheel like that,AMG style one
Hope this help

Ehh no idea but i think it was a replica
You can trade in in Klang Tyre shop for your old wheel/tyre
Can put on mudah/forum to sell too
Or keep it in future so you can sell your aftermarket wheel/tyre separately with car

Try lurking around mudah.my,zerotohundred classified section
If you want specific model/colour/offset than you have to arrange order liao

JJ is the wdith of your wheel
Offset is the centerline of your wheel relative to your hub(If 0 offset mean your wheel centerline is same as hub)

For FF car it's alright
A lot of FF car for track use wider front wheel/tyre one
Heck Cyber EVO even did wider front wheel than back last time
This help in reducing understeer in FF/AWD car

Personally i would prefer same offset and tyre size
Can rotate as you like without dismounting the tyre
For City,try 205/45/17
Close to stock rolling diameter

No,Vossen does not make any wheel below 19" IINM
Around your budget best bet will be Lenso or Advanti or Enkei Tuning
Those probably cost nearer to 1K though

Yes 15" Vossen 100% confirm imitation product
The brand i listed have mixture of original design and replica
They are Thailand made wheel i believe and have good reputation for cheap and cheerful wheel
Some even manufactured using MAT technology licensed from Enkei which is good

Vossen 17" is all replica,make sure you are aware of that