Welcome to the forum.
I'd repeat the comment about saying where you are from as it could open the chances to see kit in action and make a much more informed choice. As I understand things at the moment, then potentially there's the Aristocraft Train Engineer, Bachmann Dynamis, LGB MTS and Massoth. There are almost certainly others available, especially in America to judge from what I see in the magazines. I know very little about the Aristocraft and Bachmann products so won't comment. I currently use LGB MTS and therefore know most about that system.
Here is a starter that was posted about the LGB MTS system:
http://www.gscalecentral.net/product-reviews/a-user-s-guide-of-the-lgb-mts-system.html < Link To http://www.gscalecentral....he-lgb-mts-system.html
It's a bit dated and I would say that parallel kit is what you should be looking at. This is normally identified by a P suffix or a P sticker if converted from serial.
To try and put it in into context then the basic starting set would be:
a) A central station, a transformer (5A) and a (tethered) controller. Your loco will also need chipping with a decoder and if you want sound then either an additional sound decoder or a decoder that includes sound as standard.
Look at the picture in the system or browse around the web.
The 55016P controller - with the dial for speed is the most intuitive for speed but will not control points.
B) To control points then you need a decoder that will change point motors. In the LGB system these come either in single version or multiple(4) versions. To change points you need a controller that will do that. The 551016P will not. The 55015 will, but has the arrow buttons for direction and control rather than a dial. The 55015 also has some programming capability.
C) Upgrades.
I found myself wanting to go wireless very shortly after getting the kit. This requires a wireless receiver - that links by cable into the central station, and a wireless transmitter for the control.
Should you want to add more controllers for family and friends to play, then aside from another loco for them to use you will need another controller.
The LGB Central Station II (55005) - will take 4 tethered controllers (although there is also a socket for a booster). A wireless receiver uses one of the sockets, but will receive signals from multiple controllers.
The LGB Central Station III (55006) - will take 3 LGB controllers, and 1 Massoth Dimax Navigator contoller.
Currently on an LGB controller you have 10 buttons that can do things, although two are used for specific functons - 0 changes the loco ID that you are controlling, and 9 turns the lights on/off. That gives you 8 buttons to use, one of which will normally be sound on/off. If you are looking at a sound/smoke decoder that does more than 7 things then at the decoder fitting/programming stage you will have to choose what you get.
The Dimax Navigator, which will only work the LGB MTS 3 station, will offer you 16 buttons (some need to allocated as above) and will let you change point decoders. It also has programming capabilties. It is an expensive item though, would need its own seperate wireless receiver, and has a much steeper learning curve than the LGB items.
The Massoth site gives details of their sound decoders (you mention sounds) and the pre-assigned function buttons.
I suspect many people have gone my route which is LGB MTS and then after some time add the Dimax Navigator. Because of NMRA standards then I believe once a loco is chipped it will work across systems by different manufacturers (can others confirm this is true) ?
Massoth central stations are much more expensive than LGB ones and (I beleive) much more powerful and flexible. In terms of future proofiing then the Massoth Dimax Navigator will work with a Massoth Central Station. Because of the cost issues then I would not regard Massoth equipment as somethingI would suggest for a newcomer.
I do not know (can someone more experienced comment?) if there is a gadget that lets LGB controllers work either tethered or wirelessly with a Massoth Central Station? I think there is but not 100% sure as I do not own a Massoth Central Station.
As others have said, everything uses power if drawn from the track - motors, lights, smoke units, sounds. I found it hard to stop at just the two locos that came with my LGB starter set.
There's a few postings about DCC on my blog -look for the DCC label. I want to add more "sound" videos but am still waiting for the delivery of my rolling road.
Chris