ajax beginner: if is easy answer yes/no

[leonidassavvides]

Please if is easy answer yes/no:
I must make 3 js functions[fillNewsInfo()] that call SEPARATELLY httpRequest1.responseXML, the other httpRequest2.responseXML, and the other httpRequest3.responseXML, ...for from one html file open more than one xml file eg 3 (with php combined), from 3 websites and appear all results on screen same time ?? yes/no

all these functions must be called with
httpRequest1.onreadystatechange=fillNewsInfo1;
httpRequest2.onreadystatechange=fillNewsInfo2;
httpRequest3.onreadystatechange=fillNewsInfo3;
in the updateNewsInfo() function ? yes/no
What if one of this fails, result (table cell) will be empty ? how delete cell if fails the ajax response ?

I can do this [include multiple functions] asychronyously only ? yes/no

May do a function BUILDS get httpRequest objects with a parameter like:
function getRequestObject(httpRequest) {
httpRequest = new XMLHttpRequest();
}
? yes/no

A textbox <input type"text" name="first" /> when submitted without touch it or get focus to it[hence is empty] will have $_POST['first']=null or "" or undefined ?

clearInterval(timer); in js will cause error if timer action stopped from before ? timer no exist...

[leonidassavvides]

answer asap this and if easy the above:
i)in js in a for loop the counter to increment one by one must be ...,++j or ...,j++
ii)null value considered and the value="" ?
iii)to set css text color to Transparent what to do ?