The answer to the first question is...when formatting, you do not wipe clean the master boot record. The MBR still has the info in it from the previous install. If you wish to totally wipe the drive clean, I suggest you download clearhdd, you can find it doing a search on google.com and getting it from any drive manufacturer that happens to pop-up.
As for the second question, it is a server, therefore it must establish which machine is the "head honcho" even though it is not on the lan and is the only machine up and running, it does not know that and will therefore hold an election to determine which machine is the master browser. The master browser is the machine that holds the list of which services are offered where, ie...which server is the print server, the app server, which server has any particular service to offer. When other puters connect to the lan they seek the master browser to get all this info.
Mike