求教8老師：About using EAD card

My current H1B will expire on Sep 1st. I485 is pending for three months. I am thinking to use EAD card instead of renewing H1B. Here comes a few questions.

1) My EAD card is only good for one year. So, if I485 is still not Current within one year (or hasn't processed yet) and I have to renew the EAD card, can I renew it by myself without an employment letter (i mean if I don't have an employer at that time)?

2) If I use EAD cross the border (say, Canada to US), will I get a new I-94 even if my current I-94 associated with H1B is still valid?

Thank you.