events setup for a many to one calendar relationship

Event organisers X 150.

All events need to display on a central calendar as all viewers have an interest in the same events no matter who has entered them..

Is it more beneficial to

MULTISITE – (most organisers have little need for a site but need to display time and place)


SINGLE site with 150 organiser users.. (they each own their own events and need to take their own payment for some of those events)

1 – when they each enter their own details will it go to a central calendar?

2 – front end editing – is this restricted to their own events?

or can they access any event.

NEWSLETTER integration – the central body needs to send emails of updates new etc entered by all organisers on a given time/date basis. (ie once a week or whatever)

Is this possible.