Any linux box can be used as a normal fta box.
Lets be honest as well - most folks start with them fta only. Indeed many of us still only use them for fta stuff just because of the additional tweaking you can do with them (re skinning the graphics if you dont like the base image etc).
Of course they have the more advanced functionality but thats something that can be tinkered with if your interest in the hobby takes you in that direction.
As Im sure you are aware c/s is a distinctly grey area and whilst we will give a limited amount of help for anyone wanting to set their own up, if you decide to go for a pay server you are on your own as that area is completely off limits on this forum so you wont get any help sorting out problems.
To be blunt only a fool joins a pay server anyway - they are run by the scum of the earth using distinctly questionable methods at times. And if the server gets busted your IP is on the server logs plain as anything for the authorities to trace.