There are a ton of custom-scenery add-ons that will drastically improve the aesthetic appeal of your park. You can find some links below.
Vodhin's Community Pages:http://www.vodhin.org/e107/download.php?list.3
The Complete RCT3 Custom Scenery List:http://www.rct-theme-world.de/rct-liste/complete-list.htm
There is no Roller Coaster Tycoon 4 instead it will be Roller Coaster Tycoon 3D for the Nintentdo 3DS.
Every higher version of Roller Coaster Tycoon, has more rides, more scenery and many other things.
Platnum gives you access to Roller coaster tycoon 3, Roller coaster tycoon 3 WILD, and Roller coaster tycoon 3 soaked, If you just buy gold you cannot do anything on roller coaster tycoon 3 WILD like have a zoo and the WILD themed stuff such as deco's and rides.
Not that I know of but there is roller coaster tycoon 3.
You can buy roller coaster tycoon for Mac. It's 49.95
All Roller Coaster Tycoon games are computer games
Nope
Roller Coaster Tycoon 3 is the latest one for a computer and also for Mac.
No, they are two entirely seperate games.
go to en.softonic.com and on mac search roller coaster tycoon 3 and will be downloaded from a external source
No, But they are coming out with Roller Coaster Tycoon 3D for The Nintendo 3DS May 22, 2012.
I think you will have to start from the beginning of your location in Roller coaster Tycoon 2.