[svandamme]

didn't even notice the "offer it to patients " thing

in that case, you'll need a seperate DSL , anything else is just a liability

price wise, new DSL line and subscription , low bandwith or high , depends on how happy you want to make your surfers ( lower = less attractive for abuse, who needs 3 mb/sec for email, i sure don't )

+ 1 basic internet router, 50-100 USD, no more

no need to secure the wifi, just configure the name, and post the config data with a disclaimer "use at your own risk, absolutely NO guarantees"

done

nothing changes in terms of office data security, sine you don't touch it, anybody accessing it from the wifi ,has the same security hastles as anyone now trying it from the Internet