1) Nodes are announced over the network by me via transactions. No hard fork is needed to implement this, it's a simple matter of
a. Node owner contacts me asking if they can be announced
b. I check their security, ensure everything is configured properly
c. I receive their public key and addresses
d. Using my special announcement address I send a transaction to another of my addresses, with the mixers public key + addresses embedded as 0 value transaction outputs (along with flags in the data saying if it's being announced or revoked)

Embedded TX data looks like:
[4 byte flags field]
[256 byte node public key field]
[20 byte node receiving address public key]
[20 byte node sending address public key]

e. Clients see this transaction, check if its from my announcement address then decode and add the mixers public key, along with the mixers receiving address and sending address to a list of mixers built into the daemon
f. New clients, while downloading the blockchain, when they see a transaction from my announcement address they do as above.

2) Node revocation works much the same way as above, except the flags field specifies a removal bit and the receiving address, no need for public key or sending address

3) Automated way of checking if nodes actually send out data, works like:
a) Someone sends a TX to be mixed
b) Network sees the TX being sent to known mixer receiving address
c) Clients on network keep a tab on the mixers sending address to make sure it actually sends coins with equal or more value out in the next 8 (extra minute for slow networks) minutes
d) If it doesn't the node must be offline and it gets removed from all the clients mixer lists
This would also apply while people download the blockchain, the only way to be readded is for me to issue another node announcement.

4) A ping-pong system to check if nodes are online, receiving nodes that get added by me get added to a script that automatically sends 1 coin without any mixing data embedded. Works like
a) My script sends receiving address 1 coin, with a 0 value transaction output specifying my own address (in a format different to normal mixing data, this wouldn't be encrypted and would only need a single output)
b) Receiving node receives the coin, does the normal mixing procedure
c) Sending node sends the coin back to me
d) My script marks the node as still online

If I don't receive the coin back then the node must be offline and a revocation message is issued to the network saying that the node can be removed.

TODO:
1) make mixer scripts allow for transactions with value of 1 to be sent to the sending node and sent out without any fees or encryption of the tx data needed
2) set the encrypted mixing data (when decrypted) to be completely random and then write the mixing data over it, along with the number of tx's to send.
3) ??? (TBA)