Once I have virtualized version 8.6.1 of Unity Connection, in order to upgrade to version 11x, do I need a bootable or non-bootable .iso? Also, TAC told me I need the ciscocm.refresh_upgrade.cop file before upgrading to version 11x, but from what I can tell in the documentation that file is only needed if you're upgrading from version 8.5x and earlier, not 8.6x and later, correct?
You'll need to get the media from PUT for that upgrade path, and you won't need the refresh COP, but you will require other COP files.
Make sure to read the upgrade guide, RNs, and new and changed information to understand all the pre-reqs, procedure, and post-upgrade changes.
you don't need a bootable ISO for upgrades only for Fresh installs. I see 11.0(1a) available in cisco.com so that one will work (not tested it yet but that has been always the case). As Jaime mentions, you still need to run through PUT with a valid SWSS contract to get the order in place and be able to have the licenses migrated.
You don't need the refresh upgrade cop file either, only ciscocm.version3-keys.cop.sgn.
HTH
Isidro