Do not run two av's even if one is turned off as the low level driver's will conflict, yes you can run a realtime anti spyware malware along side avast with no problem's, i would recommend malwarebyte's pro as being one of the best that there are for a $20 life long license or just the free if you dont wish to buy but the benefit's of pro's realtime and ip blocking are well worth it. You can alway's just run window's defender alongside but i find defender quite weak and never detect's anything.