The Arduino IDE is fine to begin with. Eventually you may want to grow into dealing with more of the family of Atmel chips, tiny85s can be fun for miniature projects for example.
You'll start to outgrow the Arduino libraries at some point though and may want to switch to the Atmel compilers directly.
For resources the Arduino.cc forum and tutorials are a great place to start. Should be able to find some project ideas as well.
For resources the Arduino.cc forum and tutorials are a great place to start. Should be able to find some project ideas as well.