The short answer: As often as your plants need it.
Watering requirements will depend upon several factors: the soil condition (and its ability to retain moisture,) weather (amount and frequency of rainfall,) and the water requirements of your particular crop. The best way to tell is to know your crop and the indications each particular plant will give if they are thirsty or over-watered (hence,t he short answer.) Additionally, in the U.S., the USDA has Cooperative Extension offices in each state. These offices provide (free) information on typical soil conditions in your particular area with additional information on each specific plant based on these soil conditions and the climate. See the link below to find one nearest you.
about an eighth of a cup daily.
How big is the garden? Where is the garden located? Climate zone? How many plants and what types of plants are in the garden?
Yes you can water your garden to much so be careful, you don't want to drown your plants.
in a garden we should be careful of thorns and insects. it takes more water.
Depends on the plants
In the evening or while it is raining.
Depends on the size, contents, and dimensions of your garden. if it is classed as a small garden it would be about 100 letres, if it is classed as a middleish garden it would be about 500 letres and if it was classed as a large garden it would be about 1,000 letres
That depends on how hard the water is running.
Flowers should be near a source of water such as a garden hose.
MOSQUITOES BREED IN GARDEN WATER
You should not be drinking from a garden hose. They can leach chemicals into the water that are toxic. If you are trying to eat the garden hose, you've got some problems.
You need to know your growing zone. You need to know the type of soil you have and how much water is available in the ground. You need to know how much sunlight you have where the plants will be. You should have a plan showing the use you want of the land and the elevation (water drainage) to make the best decisions of what plants to buy for your garden. Set a budget so you don't spend too much.
How much water the average 30 ft by 50 ft garden uses is dependent upon several factors. To be considered are the type of soil, the types of plants, and the climate.