Not against
Snake Utilt.
But you need to come to the air more when fighting snake.
No you don't, not unless he's also in the air.
To play against Snake, as long as he's on the ground, you should not be entering the air because he outprioritises any aerial you throw at him, including bair (which is Sonic's safest aerial). Spindashes and dash attacks clash with his tilts so I'd say to clash with them and keep tapping A so you get your jab in first. I'm not sure whose initial jab comes out faster, but as long as I keep tapping A after spindashing, I usually hit first.
You should play a very refined game that consists mainly of spindashes and grabs when on the ground with Snake. When he's in the air though, try to keep him there and try to attack him from the front, his bair is a bit ot a problem.
I think it may be best to get Snake off the edge with a low trajectory attack like Dthrow or dair, then pursue him but don't attack him. This will usually pressure the Snake to move backwards on his cypher as to avoid getting hit. You can try edgehogging or regrabbing him when he lands.