Hm, well the good news is once I get the pins into my 20 pin socket they seem to go in and out without too much difficulty... and I don't need to worry about bending them like with ic pins, so maybe pulling the arduino out to program it will work for me.
I'd still like to understand exactly what I can and can't do with the serial pins though.
Also, if pin 1 is set high when the arduino is reset, and shutting off the power to it is the same as a reset, then does that mean when I turn the power on, pin 1 is going to be high?
If pin 1 is high, and I have an led on that going to another pin, and the other pin is set to an input state... then the led is either not going to light, or will light dimly, correct?
How long after I apply power to the arduino does it take for the program to start running so I can set that pin to some other state?
If that's the case, then I'm guessing that those pins which are set to input, a high impedance state, are going to ground through a large resistor.
Sort of only it means they are effectively disconnected.
what you mean is that it's okay to connect a load with a lot of resistance.
Yes.
What I don't get is why that means an led is okay, but something else with a resistor in series is not.
No an LED is not a high impedance load. An LED is a load, it can be quite heavy (low impedance). If you put a bigger series resister with the LED it can make it a higher impedance BUT it has to be a much higher resistance than you would normally use and the LED will be quite dim.
and shutting off the power to it is the same as a reset
No shutting off the power is turning it off, it is not resetting it.
when I turn the power on, pin 1 is going to be high
When you turn the power on all pins are inputs (high impedance), when it starts the boot loader program makes it into an output and sets it high because that is the state of a serial line sending nothing.
How long after I apply power to the arduino does it take for the program to start running so I can set that pin to some other state?
It is about 3 seconds before the boot loader decides it is not going to get a new program and so runs the existing one.
No shutting off the power is turning it off, it is not resetting it.
I was told by someone else shutting it off is the same as resetting it.
Both resetting it and cutting power seem to put the arduino in a state where it will accept new programming, so what's the difference?
It is about 3 seconds before the boot loader decides it is not going to get a new program and so runs the existing one.
I have found that when I plug in my USB cable only partway, the program runs immediately. Are you saying that is not how it will behave when I simply apply power to it normally, without the breakout board attached? Why does it behave that way in this instance?