How many Masternodes are active?
Where it can be check at anytime?
Are BRO invested in Masternode just spend or those can be recovered?
Here you can check the stats of the Masternodes:
if i unserstand your question right, then you do not spend the BRO for your own msaternode, they are only locked the time you run the masternode.
If you quit the masternode, you can use the bro.
app menu > help > debug window > information > network > number of masternodes
it's not a spending, it's deposit (or pledge). you can create additional bro-coin address in your own wallet and send pledge to it, info of this transaction got to be used in node settings (node.conf). on youtube you can get some howtos about starting a bro node. pledge for node is 2500 bro, and, of cource, you need a server too )