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I need to drill 3/8" diameter holes, at a 45 degree angle, into my poured foundation basement walls to inject polyurethane, in order to prevent shrinkage cracks from leaking ground water. There is rebar in the walls, but I do not know to what extent. The drill bit needs to go 5" into the wall at that diagonal angle. What is the lowest amperage needed for a job like this?
I am looking at around 80 holes.
Any true concrete drill like this 4.2A Makita will work. Any drill with a chuck that takes an sds-plus bit should work. 3/8" holes are not particularly a big deal.
Some "hammer drills" have a regular drill chuck that you can use a masonry bit, but you would likely be just as well off using your forehead. 
0 Amperes. Grab a star drill and a hand sledge and your safety glasses and ear muffs and have at it.
Now, if you'd like to do it faster, you might want more. If you are mainly doing this one project, then see what your rental center has for a hammer drill to rent, and use that, and return it when done. Other than that option, any hammer drill will do it, and most non-hammer drills will also do it, slower.
It's not about amperage...
Hammer drills are garbage. In a hammer drill, the whole chuck moves back and forth, and that imparts some motion the the drill bit. Most of the power is wasted moving the chuck (which is heavy) back and forth, and very little power ends up doing useful work.
So instead you get a rotary hammer with a SDS chuck. This has a pneumatic hammer hitting the back end of the drill bit, so it is like hitting a chisel with a hammer. Most of the energy goes into the useful job of drilling the hole. It's much faster.
How fast a rotary hammer will drill depends on the impact energy (in Joules) which is mentioned in the product description. 2 Joules is fine for light work (up to 15mm diameter) and also not expensive. For big holes like 20mm or more, get more joules, but the tool will be heavy and more expensive.
With 2-3J tool and a 3/8" (10mm) bit in concrete you can expect about 15-20 seconds for your 5 inch hole. Maybe 30 seconds if the drill is a bit anemic. You don't need to buy the drill, you can rent it. Rebar is not a problem with these, you will feel a resistance when it hits, but it'll chew through it.
These kind of tools use less than a kilowatt, so that'll give you the amps, if you're worried about that.
If you've never used one of these:
Wear eye and ear protection
Always both hands on the drill with a firm grip! the bit will seize in the hole at some point and the drill will rotate. It has a clutch, which will do its job, so you will be able to hold it with two hands, but if you hold it with one hand, you might fall off the ladder or hurt your wrist.
To drill at a 45° angle in concrete, first drill a few mm at right angle to make a starting hole so the bit doesn't slip along the wall, then slowly angle the drill to the desired angle.
