Help appreciated. Pump runs fine until hose attached.

[benspot]

The facts:
1. Pump runs around 20 - 25 psi. Ok??
2. Two returns, two intakes (skimmer and main drain). Generally I just use skimmer and sometimes switching between them or screwing with valve causes problems.
3. Water basket fills 2/3 to 99% generally.
4. Return pressure low. Sometimes just bubbles then nothing.
5. Hayward pump with DE and fingers.
6. I note small leak under pump itself.
7. I have 2 brand new hoses, same issue either way.
8. I replaced o-ring/gasket just to be sure.

The Issue....
When I attach my hose, water-primed, the basket empties and the pump just sucks air. When not attached, pump works fine though return pressure is
fairly low. Seemed to be working when water was very high and hose was covered above plastic 'cup' in skimmer. However, with water that high skimmer can't skim. Not the hose, bought 2, have tried 3.

Perhaps related...is it normal to hear water trickle out of basket and back through valve into the skimmer intake connection as soon as the pump is turned off? Wouldn't there be 100% water so perhaps a leak?

Objectives...
1. Correct issue so I can vacuum.
2. Increase pressure of returns (unrelated?)