php - SQL query issues: [1] Count(*) and [2] using NOT vs <> -

i have been staring @ code long starting bleed together. let's couple things out of way:

1. i low-moderate level sql user , still learning best ways accomplish queries , such
2. i have been building php based quote-generator tool ties in sql database

now, here trying accomplish: have pagination results of quotes have been created status not "dead", "duplicate", or "signed" , id not equal 999 (because wanted quotes jump 1000 , did not build database correctly @ first)

here have accomplished: able create basic structure , works fine on page 1... goes sideways. thinking count(*) query, seems fine - functional, @ least:

$countqry = "select count(*)               needsassessment               id <> 999                 , status <> 'dead'                 , status <> 'duplicate'                 , status <> 'signed'";  $countresult = $mysqli->query($countqry); while($rowq = mysqli_fetch_array($countresult)) {     $totalrows = $rowq[0];     $each = ceil($totalrows/$limit);     $where = "where id > 0";     if ($totalrows == 0) {         echo "you have not created quotes.";     } }  $limit = 15; if (isset($_get['q']) && $_get['q'] !== "") {     $offset = $_get['q']; } else {     $offset = 0; }       $query = "select * needsassessment $where           $and              , id <> 999              , not status = 'dead'              , not status = 'duplicate'              , not status = 'signed'            order id desc limit $offset, $limit";  $result = $mysqli->query($query); $row_cnt = mysqli_num_rows($result); if ($row_cnt == 0) {     echo "you have not created quotes."; die; } if (!isset($each)) {     $each = $row_cnt/$limit; }  if ($each > 1) {     echo "<ul class='pagination'>";     for($i=1,$y=0;$i<=$each,$y<=($each-1);$i++,$y++) {           echo "<li><a";         if ($offset == ($y*15)) {echo ' class="active"';}             echo " href='?q=".($y*15)."'>$i</a></li>";         }         echo "</ul>";     } 

okay, here questions:

1. i saw using php's mysqli_num_rows() wrong , should use sql's count(*). why? have different result or take longer?
2. what going on page's 2 , 3? when row count says sees 15 rows showing. have records (i.e. status of "signed" or "dead") excluded list , thinking may have been issue, doesn't seem matter on first page.
3. what difference - if there 1 - between "not" , "<>" checking records?
4. if have suggestions or if have done blatantly wrong or inefficiently please let me know can correct :)

thanks make stack overflow awesome!

edit: there code missing:

if (!isset($sst)) {     $where = "";     $sst = ""; $countqry = "select count(*) needsassessment id <> 999 , status <> 'dead' , status <> 'duplicate' , status <> 'signed'"; $countresult = $mysqli->query($countqry); while($rowq = mysqli_fetch_array($countresult)) { $totalrows = $rowq[0]; $each = ceil($totalrows/$limit); $where = "where id > 0"; if ($totalrows == 0) {echo "you have not created quotes.";} } } else {     if ($option !== "*") {     $where = "where ".$option." '%".$sst."%'";     }     if ($option == "*") {     $where = "where status '%".$sst."%' or title '%".$sst."%' or proptype '%".$sst."%' or pstype '%".$sst."%' or createdate '%".$sst."%'";     }     $offset = 0; }     if ($_session['admin'] >= 1) {     $and = "";     }     else {     $and = "and creatorid = '".$_session['user']."'";     }