Well to just add/update roms and edit files, the remote administration is not needed. You can just share the files on the network. One thing to consider is how do you feel about running a network cable to the cabinet? If you don't like the idea of that, then you can go wireless, but wireless is significantly slower. So if you were to be transferring large amounts of data, its gonna take a while on wireless. If its accessible, you could just run a cable to the computer whenever you need to update. As far as software, you don't need any added software unless you're trying to things such as shut down the arcade computer from another computer terminal. Or another example would be trying to start your front end or emulator on your arcade computer, but trying to do it remotely from another computer. I doubt you need to perform such tasks, but if you did, then you would needed added software. I hope all that didn't sound confusing. If it did, please let me know. But as it stands now, i'd say all you need is a network card for your arcade computer and a network cable.
-Kevin