Ian:
You Asked:
Some very basic questions about the mobile station (sorry).
"It can run up to 10 trains all at the one time."
Yes... with the older Mobile station you can control up to 10 locomotives. This is due to the fact that the mobile station can only store up to 10 locomotive addresses in it's buffer. Apparently with the newer mobile station the buffer can be increased to 11 locomotives with the card reader option. But... as Darren said, this take a lot of power to do. More than a single Marklin Trafo can supply.
You asked:
"If say 10 trains running can you stop 1 reverse it and then travel in the opposite direction,while the others carry on."
Again, yes, in a digital environment power is now supplied continuously to the rails, which is why a greater amount of power is needed for your layout. Instead of a rehostat controller supplying power to the system in incrimental units (ie: the more you turn the knob, the more power you feed to the system) power is now continuously fed to the rails at a constant level. To test this, just place one of your older locomotives on the digital tracks and it will take off at a very fast speed and it will be uncontrollable. In order to control the locomotives the controller (mobile station/Central station) "communicates" by way of a decoder located in each locomotive which is designated by a specific address. The controller then "issues" commands for said locomotives/address (either foreward, reverse or stop). As was stated, the mobile station can store 10(11) locomotive addresses, while the Central station can store considerably more. While I'm not sure just how many it can store, I know that it can store up to at least 80 but I I've heard it can store more and I'm sure that someone on this list can tell you the exact amount, suffice to say, more than anyone could conceivably need or use
You asked:
"Can it run a mixture of track and overhead loco's at the same time."
I'm assumeing that by overhead loco's you mean Catanery, if so the answer is again, yes, although due to the "somewhat flimsy" connections between the Cat wires, Marklin doesn't recomend using this set-up to run locomotives as the connections cannot ensure the proper conduction of the digital signals to your locomotives. (Although, on an aside note, Catenary is the one instance that you can use your older "analogue locomotives" with a digital system. Due to Marklin's common ground system, you can supply an analogue signal to the Catenary wires and use the common ground as a return to your transformer.)
You asked
"Can they be isolated from each other using M track (say 4 stations)"
This one is difficult due to the fact that I'm not sure what you mean by "using M track". As far as using 4 stations, and again, I'm assuming that you mean 4 mobile stations, the answer is no.
Each mobile station requires a separate source for power, which would mean combining 4 separate transformers, something that is not recomended as it would cause a cumulative incriment in power to the layout which would cause at the very least a burn out of your system (damaging many expensive locomotives/solenoid equipment) or... at the worst... a serious overload of household electrical systems which could result in serious electrical shocks.
If you choose to go the route of a Central station (which I would recommend) extra Mobile stations can be connected to the system through connection on the Central station or through a special connection box (sorry, I don't have the part number at this time, but a dealer can tell you what the number is)
And lastly, you asked:
"Can they control points/signals."
The answer to this is yes and no. That is... with the older Mobile station, the control of the solenoid or control points was/is not possible (again, due to the buffer size). With the newer Mobile station the control of solenoids/control points is now possible.
If you are going with the older Mobile station for controlling your layout, you will still have to control your solenoids through the older (tried and true) control box set-up. The good news with this is that if you are using the control box system you can use any older "analogue" transformers to supply power (separately) to the control points.
That is, just don't ever...ever... ever hook up a "red" wire from your analogue transformers to the "red" wire of a digital transformer.
Hopefully... this helps. If you want more info, feel free to contact me offline anytime, and good luck!
Thanks for any help.