Biggest thing is to not 'over think' the contact response; it is not life or death or even, make or break. To simplify, it is just a chance for you to learn a little about the coach, the program and the university.
Best way to get your feet wet is to just use emails; there is a certain disconnect with emails which can create a comfort zone. With the emails you received, respond with something along the lines of, "Thank you for your email and I am excited to learn more about your school and program." Then, give them a brief snap shot of how your junior year of club volleyball went, and an update on any summer tournaments you are attending. Follow that opening with just a couple of general questions about their school/program; how did the spring season go, academically what are the schools strengths, what summer club tournaments will you be attending?
When you are initiating contact or reaching out to introduce yourself to schools you are interest in, it is even easier, "Dear Coach, My name is Mary and I am a Junior OH hitter from Waxahatchie, Texas and I play for Club Super Duper" (if I ever develop create and coach a club volleyball program, I believe I will actually name it Club Super Duper!). Tell them you are interested in their school and volleyball program and would like to learn more. Make sure you attach a bio sheet to the email, so they can print out all your contact and personal information. Last but certainly first, is to include some type of video with your outreach email - Either hyperlinked to the bio sheet or linked in the body of the email; you gotta include video because that is the best way to garner a coach's attention.
I also suggest you keep an eye out for my live webinars I am re-starting this month; they will be approximately the middle of each month this summer. In addition, you may do well to search through past posts under the label, Recruiting Communication. Or, if you really want to be a classic player, you can grab my Inside College Volleyball book!
Also, if you click the NCSA logo box, you can sign up for the free side of NCSA, which will allow you to go back and check out all the recorded webinars. I actually did a webinar on the introductory letter and the telephone call to coaches.
Good luck and just contact them; don't think, just contact!