I've come to rely on the pelleted bait - I often sprinkle it around new plantings of seeds to keep the slugs & snails from destroying the seedlings before they can take hold. I had a bad infestation of Cuban brown snails a couple of years ago & now they're almost completely gone from my yard. I buy it @ Home Depot - most garden supply stores should have it - it's iron phosphate & breaks down into fertilizer... Thinking those in the photo might be tree snails? This article says they are not a pest... Here is a link that might be useful: Tree snails

Take this diagram as a very general idea about where you might consider placing trees. It doesn't mean you can place trees at any and all locations along the line, but that it's a starting place to evaluate tree placement. Often one tries to keep some centrally located open lawn space, but this is not a hard rule. Much depends on your specific needs and desires. You would want to take into consideration the specific tree and its size and habit, other competing features in the yard, and architectural features of the house, etc. If there are any very small trees (in the 10' to 15' range) they might go closer to the building in front of blank walls. (For these type trees I usually use multi-trunk trees that are more commonly thought of as large shrubs.)

Italian Cypress, yes. They look thirsty to me. California has been in a drought for years. They are planted very close together so they are competing with each other for root space, water, and so forth. I've got some taller than that that are 10 years old, but mine are not so closely planted so they've retained their foliage down to the ground. Trees here where the Santa Anas are very intense tend to fall when we get a wind event a week or two after a very heavy rain. This is because softened moist soil due to the rain will allow more rocking action in strong winds. Have never seen an Italian Cypress fall--usually they just die upright. Eucs, Oaks, Pines, those are the "fall guys".

I would not spend one cent on putting in grass or an irrigation system or any live landscaping whatsoever. It makes no sense whatsoever for you to spend your hard-earned money making improvements to a property that you do not own, and the money you spend can never be deducted from your taxes or re-couped in any way. Furthermore, the cost of water is prohibitive where you live, and watering a yard costs a lot of money. Once you put in a yard, you will have to maintain it, or it will look even worse. In the summer in southern California many places prohibit the watering of lawns for weeks on end because of water shortages and what you put in now will die. Right now, you were given a wasteland. That's what you need to give it back to the landlord as, unless your lease says otherwise. Please carefully read your lease and make sure he didn't slip something in about your putting in grass. If not, take multiple photos of the front and back and side yards that have the date on them, and and have the landlord sign them on the back, and you sign them too, and you keep a couple of copies and give a set to the landlord. I would add a codicil to the lease that both of you sign saying something like photographs are given to the landlord showing the current condition of the front, back and side yards with no living vegetation whatsoever and piles of dead vegetation. The lessee (that is you) bears no responsibility for planting these areas. As the dead vegetation is present at move-in of the lessee deemed a fire hazard it is the responsibility of the lessor (that is the landlord) to mitigate the hazard as soon as possible but in any event no later than 10 working days of notification of such hazard if it exists. And then you should contact the local fire house and have someone come out and see if the conditions constitute a fire hazard. If they do consider it a fire hazard, get it in writing on official fire department letterhead. Because if they do consider it a fire hazard, your renters insurance (do you have that by the way?) may not even cover your damages because they may consider it negligence. And do you really want to try to sue your landlord for the value of your posessions? And why should you have to pay someone to clean up the mess that previous tenants made? Did you clean up their dirty kitchen? NO So don't clean up their dirty and unsafe yard. For the Houzzers that are unaware, California is a tinderbox.