I've been following a text book that has shown me how to wire up an Arduino Uno to a servo using an external 9v battery which goes through a voltage regulator to bring it down to 5v and all is working fine. But in order to put my arduino to use, I want to power the whole lot from one power source, maybe a transformer or a 9v battery. I understand that the arduino can't directly supply sufficient current, but do I really need to have 2 power sources?
I'm wondering if it's OK to connect the 9v battery to the power socket of the Arduino, as well as the voltage regulator so that it is powering both in parallel?
Also, if that is OK, is there a nice way to solder the 9v battery connector to the arduino, or do I have to get a plug?