New brushes should be ok to run.. but check them regularly to make sure they aren't chipping...
I wouldn't use oil at all on the bearings.. there is not shield under them and you may get oil on the comm which would ruin the motor. Just be sure to dust them off. Oil will eat the grease in the bearings and attract dirt. You will get longer life by not using oil. Also never spray the can out with cleaner.. just dust it off to protect the bearings.
You will probably need the comm cut every 6-8 runs to keep it like new. You can probably get a comm lathe pretty cheap these days off the selling boards here or on ebay. Everybody is going brushless.. which is sooo much easier to deal with.
Brush can still be very competitive.. just takes work.