How can I still work and travel abroad despite the EB-5 program being in limbo if I have an approved EAD /AP combo card?

Yes, you can travel and I doubt they will refuse entry. The very remote chance of them not renewing makes it potentially viable to travel with limited risk. Maybe wait beyond December 31 or the end of the month. My guess is we will see another 90-day extension.

For now you can still travel freely with your valid AP. I would refrain from traveling if possible because it is not very clear what USCIS will do to your underlying I-485 if the program is not re-authorized in December.

Yes, you can travel using your valid AP and work using your valid EAD - these documents are a benefit of the pending I-485 application. If USCIS changes its policy and denies all pending I-526 petitions due to the lapse of the EB-5 program, then underlying I-485 applications would be denied and the EAD/AP card would be as well. For now, work and travel are OK with a valid combo card.

You can travel on a valid AP.

Even with your approved EAD/AP combo card, you can still be at risk of USCBP inspectors denying your re-entry into the U.S. because of the lapse in the EB-5 regional center program.

If you have a green card, you can travel. If you have advance parole based on a pending I-485, you can also travel.