So if I used radio control remote (say 7 channel just for now) I would be able to control all 7 targets separetly by the controller. Is that correct?

If the above is correct. What would I be able to make them do? (EG come up, go down. etc)
ok, take a look at this pic of a radio control set. Consists of a transmitter (top pic) receiver (bottom left). The servo(s) plug straight into the reciever and are operated by the controls on the transmitter. Imagine Marks or my demo of moving servos but instead of Marks button, or my controller making the servos move, you are pushing the sticks on the radio transmitter. Thats about it. As long as you can figure out how to make your targets go up and down from a servo with whatever linkages you need then it should work. Note that some radio control sets run into £1000's - all digital etc with many features that are used for flying planes/helicopters etc - obviously not needed here. Maybe a 2nd hand 2 chanel would be a better starting point then progress from there. A visit to a local model shop maybe and see if they have any used ones. Just a thought, how much hassle would it be running them from cables ?