HI ,
Now you are in right track :)
Yes, When master fails, Still Local controllers will continue serving AP and Clients. you can not modify the configuration.
If the Master is the License server and if fails, until and unless a new license or license renewal required by other controllers there will not be any effect of this, other controllers will continue with the license already installed.
Q : When I terminate some APs on the Master controller in Master/local/local deployment does Aruba support this?
A: Yes . 100 % supports (LMS IP should be Master IP)
Q : What is the performance of a 7205er controller? How much locals can it serve? or how much local are supported for this? How much locals and aps can I terminate on this controller (maybe someone have some experience with this)?
A: As such there is no particular number for local controllers but it depends on concurrent IPSEc sessions and as per the data sheet, A7205 can have 4096 sessions and it can manage Max 256 number of APs.
Hope you got all the answers