clerk typist civil service exam for the agency i worked for consisted of a timed typing test and an oral ranking interview only (not sure how they would construct a test to guage general clerical skills). not sure what you mean by admin/commun.(?)-we had eligibility or "benefits" staff who did both with the public and interagency, and their test was largly formatted like a college apptitude test-reading comprehension, language skills, and math (given a chart and instructions on how to fomulate the answers-then actual case scenarios to compute). any kind of people skills or theory was done either via an oral exam or by the writing of paper ("you have x amount of time to write a paper discussing how you would handle a situation involving these circumstances").
most civil service exams don't take as long as they are slotted for-but they allow time for giving instructions on how the test is to be done, checking photo i.d. (and any other i.d. or certification paperwork that they require be presented at the exam), checking everyone in and out, all the operational stuff.
i used to sit on oral boards to rank those that scored high enough on the written exams (thats one thing you may want to check on-while some classifications indicate they will do a ranking list for anyone who scores over a certain number, the reality is if they end up with an overwhealming number who do they may arbitrarily "raise the bar" and only interview a set number of applicants). if you plan on working towards a civil service job one hint i can give you is to check with each agency's h/r department and ask what their policy is for ranking candidates who "tie" with scores (wierd but it does happen)-some have data systems that randomly assign who gets the higher ranking number on the list, some give the higher rank to the earliest received application-so depending on the agency it can be to your advantage to keep an eye on their website for jobs and submit an application as soon as a job is posted (cuz if they have a rule of interviewing 10 for a position, being number 11 vs. number 10 can make a big difference).
good luck!