The terminals are combination solder-lug/slip-on terminals, 3/16 wide. The coil wires are bonded by dipping the whole lug in solder so the lugs are coated. That might make it a little harder to force the connector on, but otherwise it should work well enough.
I'll attach a table of jumper connections.
You can do the switching with two DPDT switches per transformer. One switch selects series or parallel wiring of the two secondaries (2/4 vs. 8/16 ohms), the other switch selects the tap or the full winding. In the table I added the asymmetrical wiring which gives 12 ohms. (The table shows both the 4K Stereomour impedances and the 8K SEX impedances, though this transformer is not yet used in the SEX amp.) If you only need three impedances (4, 8, 16 ohms) you could use a 4-pole 3-throw rotary such as the Foreplay source selector switch. I have not found a convenient location for any switches yet.