Killies are nice. I never think of them because I can never find them.
Yes, you can have plants in the tank during the cycling process. 3-4 shrimp definitely won't be too many. You could actually do 3-4 dozen shrimp, depending on the type.
As far as the betta pellets, I can relate. I bought A POUND of them on Ebay before my stupid bettas decided they like frozen bloodworms and live blackworms and now won't touch a betta.

I feed the betta pellets to the crabs.

I alternate between the betta pellets, leftover frog and tadpole bites, and algae pellets.
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Tina
Puffers:
Auriglobus silus x2
Colomesus asellus x1
Tetraodon travancoricus x1
Tetraodon biocellatus x2
Tetraodon nigroviridis x1
Tetraodon baileyi x2
Tetraodon lineatus x1
Tetraodon palembangensis x1
The greatness of a nation and its moral progress can be judged by the way in which its animals are treated. - Mohandas Gandhi