My sister and I are paying for our Dad's driver - Dad is in his 90s. Our Dad does not think he needs help and therefore is not willing to pay a driver (he thinks the driver is happy to do it for free). Can the estate reimburse us for these expenses prior to the estate being divided among the heirs (which is more than just the 2 of us)? The answer becomes more critical since we believe we will need to hire a part-time live-in (approx $150 - 200/day) to help out when one of us cannot be there and, again, my Dad is unwilling to pay for this service so my sister and I will split the cost.

No, the estates can not apy out anything prior to proper probate. The sooner you discuss this with the rest of the heirs the better off you will be. Dad's bills will be paid but this is not his bill since he has said he will not pay for the service. Somewhere along the line folks begin to loose their competancies and a relate frequently gets a power of attorney, you and your relatives should be doing this now. If one of you gets a POA then that person can write checks and pay your expenses IF all agree.