[CentOS] Networking Question

Hello,

I may have opportunity to obtain a Intel EXPI9404PTLBLK PRO/1000 PT Quad 
Port ethernet adapter at a significantly reduced price.

What I would like to do with it, I want to make sure it is possible and 
sane before I buy it.

-=-

Device sits in CentOS box that connects directly to Internet via onboard 
network adapter.

It pretty much only acts as a NAT router + dhcp server + unbound 
recursive DNS for the private networks.

The four ethernet interfaces on the Intel adapter then :

Private Network A: 192.168.10.0/24
Private Network B: 192.168.20.0/24
Private Network C: 192.168.30.0/24
Private Network D: 192.168.40.0/24

A will have a NAS. I can reach it from Internet (via port forwarding) 
and B and C (routing table) but from it, I can not connect to Internet 
or B, C, D. That network which likely will only have a few devices can 
not initiate connection to Internet or the other networks.

B is my trusted home network. It can connect to Internet (NAT) and to A 
(port forwarding) but can not reach C or D

C is untrusted home network. Things like my TV and Bluray player that 
need Internet access but that I don't want to have the ability to reach 
anything on B, but I do want them to be able to talk to NAS on A via 
port forwarding. I'm always paranoid about those devices on my network, 
I don't trust what they are doing. Call it tin foil but I don't trust 
them. Yet they don't work right without access to Internet (updates / 
netflix)

D when used is network for guests (will have cheap wifi attached), it 
only talks to Internet via straight NAT and can not talk to private 
networks A, B, C

-=-

Is this sane ?