Traveling from US to Italy and Slovenia

How do I safely charge my iPad, iPod and D700 batteries? I have a converter to drop the voltage, but it has a warning that it should not be used with electronic devices such as computers.

What have you folks safely used when traveling in Europe to connect computers and phones etc. up to Europian hotel voltage outlets?

Also, give me some advice in the SIM cards needed for the iPad(4G).

thanks