you don't need to keep H1 with

The reason most laywers will suggest keeping a valid H1 status is for insurance, in case your GC application is denied.

So until your 485 is adjudicated, your staying in US is legal.

Now the problem with employment is this--you should stay in the same/similar field of work that your 140 is based on, eventhough 485 based EAD allows you to work for any employers you want.