http://www.sqlfiddle.com/#!3/f5fe6/5
WITH A AS (
SELECT top(1) WITH ties Q.TechID
,QuestionID
,QuestionTitle
,DatePosted
,Username
FROM tblTechnology T LEFT JOIN tblQuestions Q ON Q.TechID = T.TechID
ORDER BY row_number() over(partition BY Q.TechID ORDER BY Dateposted DESC)
)
SELECT * FROM A
OUTER apply (SELECT count(QuestionDesc) Totalposts, sum(ReplyCount) ReplyCount
FROM tblQuestions WHERE A.TechID=tblQuestions.TechID) D