If you decide to fix your floor you might be able to use some acid to etch the asphalt and poor a layer of cement over the top. Now I know you can do this with an existing concrete floor but I am not sure about asphalt. It would sure beat busting it all out and starting over. To make the surface smooth you can purchase garage paint or use a 2 part epoxy like I did. I bought the product at Menard's, $44 per kit I think. I ended up using 2 for a 3 car oversized garage.
Electricity can be very expensive if you get in deep. One option is to have an electrician come out and explain to him/her what you want and the cost. Also ask what you can do to cut cost. I wonder if you have a fuse panel or breaker box since your house was built in the 20's. I feel breaker boxes are easier to work with but all in all it really comes down to the amperage of you box. I have 1 10 gauge dedicated line to my Unisaw but it is a 3 phase saw and it uses a phase converter. The internet will have calculations on what you need for wiring and how to split your equipment. I would bet someone on here would know the answers too. I will tell you how mine is set up.
1 - 40 amp dual pole breaker for 220V 10 gauge 4 way wire - table saw only
1 - 20 amp breaker for 110V with 6 outlets 12 gauge 3 way wire - miter saw, shopsmith, dust collector, air cleaner.
1 - 20 amp breaker for 110V with 6 outlets 12 gauge 3 way wire - rest of miscellaneous power tools, i.e. drill press, jig saw.
I pulled a permit, ran my own wire, and hooked everything up to the breaker box and outlets. Not a difficult task you just need to know what you are doing and make a plan on paper and follow it. And my neighbor is an Electrical Engineer so that helped.
For heat I do use a electric space heater. I have 2X6 exterior walls and R-18 insulation in my garage. That little heater works well but it does eat alot of electricity. Make sure the heater will not start a fire if dust settles on the coils, if electric.
I have wanted to install one of these but haven't gotten around to it yet.
http://www.heatershop.com/propane_garage_heaters.htmlGood luck and keep us posted