Squashes and beans seedlings

The second attempt at green beans is working at much better since I planted at recommended correct time of year.

Attempting squash for the first time too.

Advice states planting right time will help me avoid squash borers and pests.

I do see squash leaves were attacked by probably aphids. So I sprinkled DE around each plant.

Questions/ advice:

*Should I reapply DE after it rains? (And it rains almost every day)

* should I start a fertilizer for the green bean and summer squash seedlings?

* also see picture of sad looking yellow leafs of my banana pepper.

It does not start off well.

Recommendations for fertilizer?

Central southeast florida