So 0.9 adds the ATM at the base where you can redeem points into physical bills/coins, but is there any way to convert those bills back into points or is it a one way change? So far the bills are only useful for the vending machines and that's it

You can hold a bill and Left Click the ATM to add it to your points, at least that is how I found to add them. One at a time kinda sucks but I will take it over having to sale a bunch of sell guns to transfer funds from one save to another.