1) Welcome to the party!
2) when you post, please post your entire configuration including (but not limited to) your installation method and vicidial version with build.
this IS a requirement for posting along with reading the stickies (at the top of each forum) and the manager's manual (available on EFLO.net, both free and paid versions)
You should also post: Asterisk version, telephony hardware (model number is helpful here), cluster information if you have one, and whether any other software is installed in the box. If your installation method is "from scratch" you must post your operating system and should also post the .iso version from which you installed your original operating system.
If this is a "Cloud" or "Virtual" server, please note the technology involved along with the version of that techology (ie: VMware Server Version 2.0.2). If it is not, merely stating the Motherboard model # and CPU would be helpful.
Similar to This:
Vicibox X.X from .iso | Vicidial X.X.X-XXX Build XXXXXX-XXXX | Asterisk X.X.X | Single Server | No Digium/Sangoma Hardware | No Extra Software After Installation | Intel DG35EC | Core2Quad Q6600
3) This is an asterisk question. Vicidial does not manage the asterisk logs, only the Vicidial logs (which are in /var/log/astguiclient and in database tables). Asterisk logging is well documented and easily dealt with - and in no way related to Vicidial.
4) That being said: I'm pretty sure you can simply delete those files any time you get bored. I think I've even done it with calls in progress and asterisk cares NOT. Test it, of course, after hours ... or check on an Asterisk forum. You can also turn off asterisk CDR logging or change it to CDRDB to get these logs in a db instead of flat file (for ease of perusal).