Mulch: questions to ask before it arrives.
1. What type of wood is it make of, what trees, leaves, etc. Some are better than others for mulch. I live in south Georgia, near the great swamp, so cypress is an easy choice here. It takes 5-7 years to slowly rot. Never use pine straw, it is a fire hazard (we actively remove it far off our property and well away from homesites) and it makes a perfect home for fire ants (they bed up in it, and buying pine straw can come with active queens in it). Pine bark floats away in heavy rains, so I don't recommend it either. Trees that are chipped and still green are ok, but usually rot fairly fast, 2-3 years. Avoid walnut tree wood mulch.
2. How much will be delivered? Critical, too much and you may have a huge fire if incorrectly stored. Yes, it will spontaneously combust. Never store huge piles of mulch.http://vdfp.virginia.gov/fire_safety_education/tipsheets1/preventingmulchfires.pdf and https://www.google.com/search?q=mulch+fires&espv=210&es_sm=122&tbm=isch&tbo=u&source=univ&sa=X&ei=L1wMU6vJG-f00QGoloDQDQ&ved=0CDoQsAQ&biw=1366&bih=643
3. How much do you really need? most types of mulch should be between 4-6 inches deep to provide weed resistance. Nothing stops wind blown seeds from germinating but if the light is blocked, it usually stops weed seeds already in the soil from germinating . Never place any mulch where it can be on trees or shrubs bark, its encourages rot, mold and bacteria.
4. PH changes: yes, its got a lot of carbon, it can lock up some nitrogen, so its a good idea to place it in pathways between the garden rows.
5. Insects: personally I have not experienced having a termite issue, but I usually don't have a lot of large piles laying around either. Using the best depth practices for it, in the right places should not cause issues with termites. Usually they prefer larger pieces of dead wood for food.
Yes, free is good, but be very sure there are no invasive tree/plant seeds in the mix or you'll soon be fighting to remove new unwanted seedlings. One last thought, lol, beware of getting stinkhorn mushrooms (the orange ones-Impudent Stinkhorn (Phallus impudicus, ) delivered if the mulch is already starting to decompose. Been there, done that.