The road of packets via devices

Hi! Im here to ask maybe dumb question and maybe not because you never know. so...
Im ready to buy new dsl router with firmware updates feature cause my old router has backdoor and maybe it have some rootkit or whatever is it already.
So here is the deal
new tplink router -tothe- zyxel firewall -tothe- wifi acesspoint with lan RJ45 acess.
So my internet acess and lan network will grow (i hope pure) from the acesspoint (witch gains interenet from the firewall (which gains internet from the router which have firmware update feature so I hope all security holes will be fixed by this way)
QUESTION IS:
will be my packets my wifi and my lan secured by the zyxel firewall? Or might be some chance bypassing this).
Thank you very much already.