Hi,
How bad is it to set my web browser as allowed application in terms of security?
Comodo already has a rule set for web browsers which you should use. By default, if your browser is trusted by Comodo, it will be treated as Allowed Application. But from what I’ve seen it’s pretty safe to let apps run as allowed application. If you want added control, set your browser on the “web browser” ruleset.
I used “web browser” ruleset until now, but a website I use daily wants to connect outside of that ruleset for a certain function. Unfortunately the ip addresses and ports are nearly stationary so I either have to give up that function or set firefox as “allowed application”. Although I have an AV software install I wasnt sure how bad this could be especially for a web browser as we usually access randon websites daily.
This website function will be useful, but not enough that I would compromise my security. I just have no clue how bad will it be.
You should create a custom ruleset then. Copy the rule outgoing application and replace the “block” all unmatching requests with “ask”, that way, Comodo will show an alert if an incoming connection through your browser is detected. So your safe. Assuming that you are also using the latest version of Firefox and that you also trust the website your visiting, you should be fine 
Ill try that