Problems with improper integrals



I want to evaluate the improper integral
f(x):=1/(a+sin(x))
integrate(f(x),x,0,2*%pi)
where a>1

The first question Maxima asks is

Is  (a-1)*(a+1)  positive, negative, or zero?

I reply p

Is  sqrt(a^2-1)+a  positive or negative?

I give p (that was a trivial question anyway)

Is  abs(sqrt(a^2-1)-a)-1  positive, negative, or zero?

I reply n (I had to do a slight calculation)

Is  sqrt(a^2-1)+a-1  positive, negative, or zero?

I reply p (another trivial question)

(2*%pi)/sqrt(a^2-1)

The answer is correct, but I wonder what kind of procedure was followed 
and I had to specify all those values.

I tried to replace a with b+1 with b positive, but I received 4 
questions again with only the first actually needed.

The issue with questions of that type is something that is planned to be 
fixed? Where can I read details about this, so I don't post trivial 
questions myself?

Another problem I had:

f2(x):=x/(1-cos(x)+x^2);
integrate(f2(x),x,0,2*%pi);

not result was presented (should be 8*%pi/3 if calculation I did by hand 
was right).
Seems like Maxima can't handle this integral.