I travelled to US on H1b from Company X, I wanted to change my job and requested company Y to apply for H1b transfer. Company Y just applied for H1b transfer while I was returning back to India. I am in India now and company X want to send me back to US.
Status of my company Y H1b transfer is "Acceptance" right now.

Here are my questions:
1. Can I travel for Company X as nothing has happened? Even if application status in Pending or Approved?
2. Shall I wait from H1b transfer decision or I can travel even in case of pending application?
3. What all issues I can face in POE while entering in US for company X (I have H1b stamped and valid I797 from company X)
4. What if I want to join Company Y after working for Company X for a while in US?