Pumping Lemma for regular languages proof doubt - Sipser Book
You missed what $j$ and $l$ are. Read the paragraph again. They are the two indices of the same state in the list of visited states. For example if some  automata goes from $s_1$ to $s_3$ to $s_5$ to $s_3$ to $s_7$, then you could pick $j = 2$ and $l = 4$, because both $2$nd and $4$th elements in the sequence are $s_3$.


They are always (and, assuming $n &gt; p$, can always be) chosen different.
$y$ was defined as the substring which takes $r_j$ to $r_l$. $j \neq l$ and you need at least one symbol to change state, hence $|y| &gt; 0$.
The substring $xy$ takes $r_1$ to $r_l$. A string of length $x$ visits $x+1$ states, so if we know that $xy$ visited $l \leq p+1$ states then $|xy| = l-1 \leq p$.