Is there a way to know how much buffer is left for FileSystemwatcher?

When I query

fileSystemWatcher.InternalBufferSize

It will give the total Internal buffer size allocated to the Watcher. But I want to know (during debugging) how much buffer size for the Watcher is left and can be used and when I use the above statement in the Event handler method (say for the write operation) it always gives me the total buffer allocated size to the Watcher. Is there any way to obtain the remaining size of the buffer?

Other Questions:

From this answer, it is clear that event is handled on the separate thread than the thread which received the event. Suppose we have many concurrent events coming for a single Watcher which is watching the file. What I think (correct me if I am wrong) the main thread which received the event information will spawn a new thread for each event and processing of events will happen on different threads. So I want to ask:

1. Will the main thread wait to finish the processing of all the events?
2. Which thread will clear the internal buffer associated with the Watcher and when?
3. I have read at lots of places that the handler method should take as minimum time as possible or we can get InternalBufferOverflow Exception. So, is it safe to assume that the Internal Buffer for the Watcher is only cleaned up when the thread(s) (I can't say one or all, but want to ask from you) which are processing the handler method has processed the method?