I own a sealcoating company but do not live in your area, To give you the sales pitch the sealer your buying at the box store is different then the sealer the we use. I use a coaltar based emulsion the stuff at the box stores is asphalt based emulsion. Coaltar sealer is diluted with water 30-40% asphalt sealer is 20% diluted with water.
The sealers need additives to be effective they need toughening agents added (latex) they also need to have sand added for slip resistance.
I run 1.5-3 lbs per gallon of sealer before dilutions. Manufactures recommend 3-5lbs that amount of sand displaces sealer so you end up with more sand less sealer it also tend shear off and end up tracking into the house.
If you do buy the from the box store get the stuff from Home Depot Laxtite? they have ties with a large manufacture that makes sealcoat and has chemists onsite to monitor the product they receive, what they do with it after they receive it, not sure, but the base product is an asphalt based product and is a quality product. They box store crack filler is also Okay we use a V squeegee to flatten it out in the crack works well.
When you apply get a small car wash brush 6" that you can screw an handle into to do the edges with do the edges into the drive about 6" you can dip the bristles into the pail to for edging. When you do the drive go against the line of site if your drive way goes straight to the garage go across the drive, so when entering the drive you don't see the broom lines. When sealing the large area of the drive get as large of broom 30"-36" pour out a large about of sealer and broom across the drive walking on top of the wet sealer to the side of the drive that is unsealed go back the other direction to clean up the foot prints this will cause you to half lap in both directions thus sealing both sides of the stones in the drive way.
I would recommend just having it done even a bad sealcoater typically ends up with a better finished product than a home owner can. I do it part time night and weekend and do 200-300 drives a year depending on the size of your drive figure 0.13-0.18 cents a square depending on travel and condition minimum charges may apply. Talk to neighbors and get a referral I would also recommend having it done by hand NOT SPRAYED I have capabilities to do both and typically do most driveways by had it tends to push the product into the low spots and lasts longer then a sprayed drive.
www.latexite.com
Also figure about 60sq per gallon not 100 they state on the pail
Feel free to send me a message if you have and questions or if you would like to talk over the phone I would be happy to help.
Scott