Off a 3B wallsplat, you can still use 44A BE - to get the third orb you do have to use BB then 2B+K BE though. So the combo looks like:
3B W! 44A BE BB 2B+K BE insert anything here.
As for your second question:
Viola's combos work in a very strange way. You pretty much launch, then loop people through reps of AAB -> Ground stun -> 2B+K BE to get max damage. Then you end with one of a few combo enders, examples:
2B+K BE AAB 66B 66A+BB <-- Max damage
2B+K BE B+K 44B <-- Gives nice Oki. You can 2A+B here to force them to block or eat it OTG, or you can just 66A+BB for more damage.
2B+K BE AAB 8K <-- For some pushback.
2B+K BE AAB 8A+B <-- Good oki, leaves them in perfect position for SET 6B+K stuff.
Now, knowing those enders, here's the thing about Viola's combos:
When you ground stun, you can only ground stun ONCE with the same move. So if you use 2A+B in a combo and get a ground stun, you cannot 2A+B again to cause ground stun later in the combo. The same goes for 66B ground stun and 8K ground stun. The only exception to this rule is the 6A+B 2B+K BE B+K 6A+B loop. However, with this knowledge, this loop isn't max damage because it wastes a ton of meter.
In any situation you would think of doing 6A+B 2B+K BE B+K 6A+B, you can get more damage off:
6A+B 2B+K BE AAB -> Any ender listed above.
If you want to extend the combo further:
6A+B 2B+K BE AAB 2A+B 2B+K BE AAB Ender, etc.
So yeah, max damage is always running people through reps of AAB -> Groundstun -> 2B+K -> Some kind of Ender. It really comes down to how much meter you want to use.