Moneydance just uses Direct connect for Bill payment, so it is totally dependent on of your bank provides that capability as a part of a Direct Connect service.
If your bank provides this service then any limit, charges etc is what the bank imposes, Moneydance itself does not impose any cost.
Moneydance does not use Third party services.
Moneydance is not sold by subscription, you purchase a time unlimited license for a specific version which generally provides a free upgrade to the next major release. Only if you upgrade beyond this do you pay an upgrade fee.