Construction lumber is dried to 19% moisture content. Hardwoods are generally dried to 8%. That is a good target to shoot for. Ash does dry a little quicker than most other hardwoods. It also has a lot less moisture to begin with.
Roofing tar will work fine, but has to be applied after the log is sawn ( don't want to saw thru it. ) It's much easier to coat the whole log end with latex paint. The main idea is to keep the moisture from coming out the ends, where it comes out the fastest. If the ends dry quicker than the middle, you get cracks from the uneven shrinkage.
For air drying:
Keep the wood at least 8" off the ground, more is better, and keep the grass cut around it, especially in copperhead country.
Keep it supported every 16"-24" for 1" boards, 30" is ok for 2"+
Keep the stack 4 feet wide or less, with 1x1 sticks perpendicular to the boards, between each layer, spaced the same as the bottom supports. The sticks should be dryer than the wood to prevent staining.
Cover the top with old roof tin or whatever, if there is no roof above it already, and put a bunch of heavy stuff on top of it. Keep the sides open to airflow, but shaded from direct sun.
On the sawing, See if you can find a portable sawmill operator for hire. Where are you located?
Also, check out forestryforum.com and woodweb.com. Tons of info at both places. Forestry forum has a very usable search function as well.