Captive Portal: Does this setup work or am I missing something?

[Guest]

The more I read on the homepage/forum, the more confused I get.

What I want to do: a captive portal, where vouchers are used and (basic) logging is enabled: voucher-number, logindate, expiredate and visited urls/ips

Now please tell me, if the following setup would be sufficient for my goal:
cable modem (ethernet) -> old pc (2 ethernet cards) <- netgear wifi router (connected to the pc via ethernet)

the wifi would appear to be open, so anybody within reach can connect, but when the user then opens a browser, the user is redirected to a login page where a voucher number can be entered.

My router is not supported by dd-wrt, it just comes out-of-the-box, can I use it just like that or is dd-wrt mandatory?

the old pc would run pfsense & squid (for the logging) and should I be able to get this running, I'd get me an ALIX-board and replace the old pc with it.
In order to save the log files, i'd remotely backup the logs with another pc

Any help is appreciated, thanks!