What plumbing required for 2 channel programmer and room stats

Currently have a condensation boiler which has a few years life left in it (serviced only today) The timer and controls of the system are very inadequate a mechanical one channel timer.

I want to replace the timer with a two channel model with separate advance and boost for water and heating. Is there much mileage to be go out of this?

How much additional kit- motorised valves, pumps etc would be required for a two channel over a single channel? What additional plumbing and wiring would there be?

If room stats were to be installed what pumps and valves would be required for each room stat installed?

When eventually the system is migrated to a combination boiler would the additional additional kit installed for two channel programmer multi room stat system need to be re-configured? Would there be a major change in plumbing?

It all depends on what you want the heating systems to do. You say you have a condenser boiler at the moment and from the rest of your description it sounds as if it should already have separate heating and hot water circuits controlled by individual zone (motorised) valves. These valves could already be controlled from separate thermostats already fitted in the heating and hot water circuits, so more info' on the full layout would be needed to give more choices on how these could be further controlled by additional appliances. If you have the type of system that must be run with both heating and water circuits on at the same time, then this is not very efficient and zone valves should be fitted so that each circuit can be controlled individually from each other. This shouldn't be to much hassle to do.

Room 'stats can be set up to control individual zone valves which make further separate circuits taken from the main flow and return pipework from the boiler, and these can be set to control the front and rear or upstairs and downstairs circuits, which every you prefer. This too shouldn't be to big a job for a competent plumber.