Child Support vs Custody Q's

CHILD Support vs Custody :
2 Questions (see below)

STBX & I have been separated since December and we have not legally agreed on Custody.
She wants 100% legal & physical custody, while I want 50/50.
I do not have access to my childen due to STBX.
Mediation failed.

In January STBX opened a Child Support case.
I went into Child Support Office and gave paystatements.
I told them Cusotdy was not decided yet.
The Child Support Office told me Child Support could Not be figured out until Custody was decided.
Q1: Is this TRUE ?

Now a month later, Child Support Office contacts me to say STBX wants to move forward on Support,
I said ‘how since you told me Custody had to be sorted out first ?’
The Child Support Office told me we can move forward ‘as if’ or ‘based on’ STBX having 100% custody.
Then when you sort out Custody you can go back to court to have Support altered if warranted.
Q2: Does signing the Child Support Agreement based on STBX having 100% custody, state in any legal way
that I agree with STBX having 100% custody ?

Permanent child support cannot be established before custody has been, however temporary child support can be awarded based on the current arrangement and will not prejudice your rights to custody.

If your ex is not allowing you to see the children I would advise you file an action for custody immediately in order to get access to your children.