During recruitment, your daughter should be asking the sororities (if this information is not automatically presented by the Treasurer/VP Finance) about the dues. This is not a rude question and the sororities are prepared to answer it. There is no "general" amount of money per semester, but suffice it to say, it seems like your daughter should be prepared to pay several hundred dollars ($500-900) the first semester and a few hundred dollars every semester thereafter. Your daughter can also ask whether or not the fees are all inclusive, or if there are extra costs she should be aware of.
Unless there is some specific clause on the VATech campus that precludes freshmen from going, sororities will often have open houses or something of that ilk in the fall. Sororities host tons of philanthropic events, this would be a good way for your daughter to support a good cause and meet the soroity women before recruitment. Panhellenic will also sometimes sponsor philanthropic/social events with all the sororities, these are another good option. And of course, your daughter can try to meet sorority women in her classes, athletic teams, campus events, etc. This is the best "research" your daughter can do to familiarize herself with women in the various chapters.
Your daughter can research the sororities by going to the various national websites. On the national websites she'll get information like the sororities' various mission statements, philanthropies, etc. All of this information could be potentially useful.
You're doing everything right already. Your daughter will be getting more of this information in time, some of this stuff she won't know until she's actually on campus. You probably don't need to figure
all of this stuff out in advance. The best thing you can do is to just be there for your daughter... you can best help her by listening and counseling her through what can be a crazy, sad, exciting, stressful process. Have fun!
