1st support for FC5 was dropped about the end of June. So no more updates will be made.
If it follows the same path of FC4 the mirrors will start to stop holding their FC5 data. So an upgrade in the near future is strongly recommended.
For finding rpms in general search: http://rpm.pbone.net/
You should be able to just download the rpm and transfer it to the FC machine.
You will find it rather difficult to run Linux or any modern os without a net connection. When you install a package there are often a large number of dependanceies that have to be installed. You have to get all of these before you can finish the install.