Welcome.
Yes you can but you will need to make each one at the 180 mark for each day that you want. in other words, you cannot call for all your days at the first 180 day. Unless your trip is sooner, then it won't matter.
You can make ADR's as an offsite guest easily. You'll get a confirmation number and be sure to write them down AND take them with you! There's only a few venues that require advance payment and even those will refund your money if you cancel within a certain time period. When you call to make your ADR's, be sure to have a few options and be flexible on times. I've always had great luck with the CM's on the phone who really try to be helpful getting you booked with what you want. Happy planning.
Another bit of advice - CMs will ask you for your phone number when you make the ADR. Give them your cell number. This way if they need to reach you about an ADR you made and you are already there you will get the message! I learned this one the hard way.