If you're ever gonna fab stuff a 1/4" chuck DotCo's are nearly indepsnible @ my work. you can put a sanding arbor on them for sandwheels, scotchbritewheels and polising discs. or use them with rotary files or any other 1/4" accesory that can tolerate high speeds. We use them for cutting, cleaing, polisihing, hand routing and more.
A good Air drill is ruthless and relible if you want to drill heavy stuff.
Impact wrenches are very good to have but remember to only use impact in the off direction.
and My other personal favorite for inflating,deflating and checking all in one;
http://www.amazon.com/Pistol-Grip-Air-Inflator-Easy-Read-Gauge/dp/B000LMKB42/ref=wl_it_dp_o?ie=UTF8&coliid=I1UQAF8LMU5GR6&colid=1M98SLUJDGLMJ