well done on the progress!
i only utilize 2 types of carries; Overhead Walks after Muscle Snatch, Squeeze Press carries after Bench.
the Overhead Walks are taking my shoulder width into new realms. they are incredible! i currently ramp up to my 3rm (Muscle Snatch) and use roughly 70% of my ramp for OH Walks. everyone will be different but that might be a good starting point!
i did a few sessions of TBDL's with TB Carries to follow.. again ramped to my 3rm, used about 80% of ramp (no straps) and got a good workout from them.
as for squeeze press carries (i can't get comfortable with bear hug carries) i'm actually using a 25lb plate, and its pretty hard!
i think you just need to make an educated guess, and work from there... you'll never get it right, without getting it wrong a few times! -just don't hurt yourself haha.
regarding straps, i try not to use them until i really need to! -but i want to improve my forearms. if you REALLY don't need/want to improve your forearm grip/aesthetics then sure, use grips.