If you are using the black soaker type hose, you must put a filter to prevent the holes from being plugged.

"how many hours for an average would people typically run it"
You must determine your evaporation rate. You can do this by accessing your local weather data or simply putting out a screen covered pan with a measuring stick in it. Determine how much your drip system will put out in equivalent inches per day. In days of about 90 I see about one to one and one quarter inch of evaporation per day. I will leave my drip on only about 8 hours. However I have a different soil profile than you, I imagine. Also my system was designed by an engineer and I don't know all the parameters he included. I can't tell you the equivalent inches in a drip system. I can calculate it for my sprinklers, but I rely on the man who designed it to tell me that for my drip.
The hose can be, and should be, just deep enough to keep it out of harms way. I would not move the hose as the roots will grow at that position. Also I like to fix it so that the tree can send its roots away if I am over watering.
You can also simply observe your tree and the degree of wilt in the leaves to determine when to water. After a while you will get a feel for it.
I think there is an irrigation forum here on the garden web.
I don't know if they make an injector for a half inch, but if not just reduce it down with pvc. Heck, we use to just siphon it out of a barrel.
When you bury the drip you must have good emiters or you will find the roots will grow right up into the emitters and cause you no end of problems.
You will likely just have to plunge in and learn as you go on this. Good Luck.

Local information would seem better for your question. My property was a fruit growing ranch for 100 years and none of the trees were ever irrigated. My little family orchard does very well without irrigation. Your soil and mine are quite different, and the trees and rootstocks I am sure are also different. We get no rain from May till October, which I am sure is not your climate. Your local county extension is in a far better place to give you advice than those of us thousands of miles away. Al

Put one of those (Melnor?) gallonage timers in your line and at least you'll know how much water you're applying. About $12, no batteries.

My emitters are 1 gal/hour, so I know the quantity applied, as it says in my post. I was kind of hoping to hear some examples of how many gallons people were applying to whatever fruit trees they irrigated, in whatever environment they specified. With all their specific information, it still could provide help to me. Thanks -Gary

Gary: www.dripworks.com has the fert injectors you are looking for. Prices start at $53. But honestly, I don't know why you would want to go to all the expense and trouble. You get plenty of rain most of the yr. Just sprinkling a little around the plants once or twice a yr is fine. If your soil is very sandy, use the slow release fert.

You also shouldn't have to water much during the rainy season as much of Fl gets 6-8 inches per month in the wet season. Even when you do have a dry spell, one to two inches per week should be plenty.

To figure how much to apply, observe how large an area your tree canopy shades at mid-day. Then figure one gallon per sq ft equals ~0.6 inch of water. So for a tree with a 36 sq ft canopy, you would need to apply 72 gallons to apply 1.2 inches per wk. If you have four 1-gal/hr emmiters on that tree, you would run the system 18 hrs/wk to apply 1.2 inches of water.

I run my system 2 to 3 hrs per day with about four 1gph emmiters/tree on trees with about a 6ft wide canopy. But in our very dry climate that is not enough water. So I sprinkle or flood about every two wks to make up the difference. I thought about going to mini sprinklers this yr on the 1/2 in tubing. But would have needed about four seperate sets because the 1/2 inch tubing will only carry so much water. That is the beauty of drip, a little water can be spread over a large area.

This may not help you at all, but you got to admit the orchard forum has more info than the irrigation forum!!

The Fruitnut

Gary: I need to correct a mistake in my post above. An acre inch of water is about 27,000 gallons. An acre equals 43,560 sq ft. So one gallon on one sq ft of ground is 43560 gallons/ 27,000 gal/inch = 1.6 inches. So if you apply one gallon/sq ft/week that would be about 1.6 inches of water. That would be enough for your climate in all but the driest weather.

You might check me on this but I think these numbers are correct.

The Fruitnut

I have used 2 gph bowsmith emmitters for years well about 20 years had 2 problem with roots pushing out emmitter for PE pipe this on 1800 pecan trees 25 peach trees 6000 blackberry plants never had one stop up there where 2 to most plants all under ground only used system for saving the plants from dry weather run system on timer had to replace timer once. I got injector for fertilizer vaccium type never like it if the line was running different pressure it pullup to much are to little amount even with 10 pound differial in psi. I never needed pressure regulator for emmitters in dry times the 2 gph emmitters would save the trees and crop ran pump 24 hours aday for about 2 months each stage 8 hours so that was 32 gallons water per plant on new planting i would put out 5 gallons a week until dry hot about 15 gallons week for first 2 years until roots spread out a drip system has been best for to use as system to save plant are crop not to make crop. If I fertilized in dry time I would put out in wet zone of emmitters. The people that I new that used the evaperation rate to water there trees blow over bad in high winds all roots be in small wet zone no support for tree. Most fruit trees die in three weeks with out water in sand soil. Always water because the pass weather never use a forecast to plan watering only use 1 inch rain are more to stop watering cycle. Each morning when get up think of plants water needs you do right thing. If call united irrigation talk to Vance are Bob in Quitman Georgia Vance is water engineer change over to rainbird pe tubing and bowsmith emmitter 2 gph you can bury all this type system as you like the pe tubing take sunlight for 20 years are more and you can add emmitters as needed. You can use 1 gph emmitters on youg trees and 2 gph on older larger trees in 8 hours 1 gallon give 8 gallons water 2 2gph give 32 in 8 hours. I like system that can add more emmitters to in later years line with fixed emmitters is ok on older trees if good one a lot drip tape and emmitter line stop up bad even with good filter system things over time get by filter system that self cleaning works best for me watching those pressure differences before and after filter is pain pressure regulator are required on trip tape any above ground pvc get algee in it so paint it black color to block out sun light.