I have a young son who has travelled extensively with me since his birth.
If taking formula with you , may I suggest you take your own purified water. Most airlines carry still mineral waters in bottled form. These contain high levels of sodium and trace minerals that aren't necessarily well mixed with formula.
Still on formula excellent suggestion is to pack it in small plastic containers or resealable plastic bags, if your sachets require scissors to open them.
I have encountered difficulties with bassinet bookings also.
Ask at check in, "am I seated at a bulkhead with a bassinet fitting?"
If you find on board you are still not seated at a fixture, remembering " you catch more flies with honey than you do with vinegar", make eye contact with a flight attendant that is female and smiles alot. ( I can say that because I happen to be one!)
Explain your many requests to reservations and at check in and they will (mostly) attempt to move you.
I'm afraid requesting a jug of hot water for you to have at your seat to heat bottles, breaches too many occupational and health safety regs. ie: A litre of boiling water in unexpected turbulence is not a good thing. I have seen first hand the damage an adults hot coffee in the lap of an infant can do.
Flight attendants can easily heat your bottles in the galley.
Have fun and happy flying!