I believe you’ve been given a few links that will provide much information for you, on top of that Malwarebytes can detect things that Avast might miss and visa versa.

Malwarebytes is also on stable 3.1 build as of a few days ago and more information about Malwarebytes can be found on their forum.

imo Windows firewall is adequate and simplest but as everyone needs are different opinions will vary.