The plants are looking very good they have great color on top and lots trichomes which is a great indicator the plants are healthy.
With the suckers I will cut the rockwool from any side to the center split open with fingers insert sucker close rockwool insert into net cup and top off with hydroton. You can also do away with the rockwool just put the sucker in the net cup and fill with hydroton all around. You don’t need to extend the sucker deeper than the net pot. I prefer getting lots of uniform roots I find this is best way. I’ve had bad luck using neoprene collars so I trashed them.
As for
nutrients for the suckers you can either go back to miracle grow at 1/8 strength or do the same with the Verti-gro again 1/8 strength. You want to water these’s a lot at first until you see multiple roots.
You don’t need to go full strength for long with the nutrients i usually go with 3/4 strength and only full strength if I see a lack of flowers but because of the set back remain at full until you think you have enough future tomatoes that will grow. In future grows only go up to 3/4 strength at the most.
You’ve done an amazing job!!! Can’t wait to see a pick of your first ripe tomato.