When you add the mulch burm it up around each plant creating a bowl effect, this will help retain the water near the shrub. for new plants you will need to run the drip system for at least 3hrs or surface water them with an extra 1 to 2 gallons a day for the first few weeks.

Depends greatly on the type of soil you have. Clay holds water, sandy soil doesn't.

It also depends on where in the world you are.

You could use 1/4” drip tubing circling it around each plant. It has emitters every 6” for better coverage. You can attach it to your 1/4 tubing using a barbed T.

Zone 5b in ontario. Soil is clay, but i have ammended the bed heavily with compost and gardening soil, so its very loose at the moment.

I will try that burm idea thank you!

edit: i also like that drip tubing idea! It might be better then the singular drip emitters

They sell it on Amazon. Each emitter along the tube puts out 1/2 gallon per hour.