Yeah those disconnects can be such a bother. And they can save your tail. Once you get used to them, you'll be fine. I add them to any machine I work on that doesn't have one. And I make up a little label to put near the ignition key when possible as a reminder (or informer) for the users. I'm confident that it has saved a few batteries and perhaps even a few machines over some time. I'd venture to say that a recent machine fire we had (a Diamond Z grinder) would most likely have been avoided had the operator used the disconnect. They did not, and we nearly lost the machine.
Glad you got it going! Now the fun begins. I'm sorry I can't give you operating pointers. I ran ours only a little for testing. We have a couple of good hands who are pretty good with woods machinery, and they take care of the use of them. About the only thing I can say is that you should always use low gear for actually cutting and bunching. High gear is only meant for roading. But if you find the books on it, it's in there.