1. 4mA sounds like the power consumption when the radio is active, and the CPU is running full-on, so not necessarily unreasonable imo. Adjusting the TX level will definitely affect the power consumption :)
2. Afaik, there is no way to simultaneously send multiple notifications, as each characteristic requires its own packets for the data transmission. However, if you setup all of your data within the same characteristic, then you can use a single notification rather than multiple notifications spread across multiple characteristics.
Power consumption will be more when BLE is active.
However please go though our low power appnotes for better management of current consumption:
Thanks & Regards,