1. Yes, you can use mnsecret command to generate secret required to run masternode (it is only for running the masternode, it doesn't allow to spend its coins).
e.g.:
mnsecret e9fd4b14508dc514a1344c5ea29903a17e645304d247002f189910ac0a755f7e:0
where argument is output (you can copy it from masternodes page)
Then add
mnstart=...
to your spreadcoin.conf where ... will be your generated secret.
2. At least instant transactions must be finished before that.
Do I understand correctly that the instant transaction is not implemented in testnet?