Well I did a little more testing using a basic switch rather than arduino, it seems that with those same settings (enabling remote syncing) as the sd400, the a570 behaves differently.
Unlike the SD400 where one press does autofocus, next does the shot. On the A570 the first press of the remote shutter button does autofocus. Then for the second press, you must press it slowly. As soon as you press it, it fires a preflash, and then as soon as you release it is when it fires the shot. However if you don't release it after about 5-8 seconds, it fires the shot anyways, or if you just do a very fast press/release for the second press, it does the same thing, waits about 5-8 seconds and does the shot.
So right now it seems not only a bit more complicated (since I use arduino, I'd have to have a completely different setup with different code for each camera), but also there seems to be no way to wait longer than the 5-8 seconds. Unlike the sd400 where I simply lock prefocus, wait as long as i want, then fire the shot. Its just unfortunately the sd400 doesn't have as good of image quality.