Internet Connection
Do you really need one? Almost guaranteed you will. But what sort? A cheap one!
ADSL is still the best option for most Small and Medium size businesses.
If you travel a lot with a laptop, then look at wireless internet connections. Wireless internet starts at around $15/month, but prices and plans change all the time. 3GB per month for a single laptop for business related activities, should be more than you need. You can get a USB wireless modem that you can plug into any PC with USB and hey presto, you have an internet connection on it. If you regularly travel to the same cities or countries, check what type of connections they have there before you shell out for one here. You may be able to use your Australian one there or it might be cheaper to buy one in the country you are travelling to.
Unless you have specific data needs, such as you are hosting websites or require guaranteed internet access, then ADSL will be fine, if you have any specific requirements, you should contact a few ISP's to see what they recommend.
Wireless v Wireless
There are two main types of wireless. One is very short
range and you connect your PC or laptop to the wireless system (usually
an ADSL router) in your home or office, the other is like a mobile
phone, where you connect directly to the internet. The above
description of wireless internet, is for the latter system.
ADSL Modems
Do you need one? Yes if you want ADSL to work. Most ISP's sell
them and it's generally best to go with those, as your ISP can then
offer basic support. Generally we recommend getting one that is capable
of being a DHCP server, Firewall, Router, Modem, Wireless Access Point
and Switch. Most do all of this these days and cost under $200. Make
sure you get it setup properly if you don't know what you are doing,
particularly with wireless. See the Security page for more details on
this.