[dsraven]

if the garage is sharing walls with the house beware that the stuff you do in the garage is going to affect the house. if you plan on a some higher draw electrical stuff going on out there you may consider a sub panel in the house to supply power to the shop. nobody is gonna fault you for some conduit on the garage walls to supply power to a compressor or welder plug.that way you don't blow a breaker in the house and have to run back in there in your dirty shop gear or bug the wife to switch it back on.
I have had the attached garage in a house we lived in for awhile. I remember that part as well as the odors in the house from whatever I was doing out there. the next house the wife said I get a detached garage. so that worked. lol.
if you have a gas fired water heater be careful with combustibles. I have been to a few catastophic events caused by paint fumes igniting from a pilot light on a hot water tank or furnace. (retired firefighter)
I like the idea of a non attached workbench compared to a dedicated bolted top the wall style in a small work area. I am also a heavy duty mechanic by trade and have found that when the workbench is larger than needed it just collects stuff, you tend to work in a small area actually. yes, nice to have a big bench, but too big collects clutter
if you could find a cabinet with doors for the flammables that would be a great idea, since the garage is attached to the house.
I have a 10 x 10 shed to store frequently used shop tools, steel, hazardous liquids like coolant etc. it keeps the clutter down. next time I will build a quonset for storage. haha.