What is the minimum one should have at their account at IB to have an account manager assigned to one's account?
IB is an execution only broker - your not going to have an assigned manager or team like you would with some brokers that are trying to up-sell you additional services. At least that has been my own experience.
I doubt they will assign account manager regardless of your size. No frills for customers. This is how IBKR keeps cost low.
Not necessarily true. We have a sales team that deals with institutions and HNW individuals as well as a professional services desk handling the same. At the same time, we are constantly building our client service team around the world and believe we have and are making strides towards providing a high quality of service to all.
The more accurate metric would be how much revenue the client generates for IB - not the amount of capital in the account. And nothing wrong with that.
We have an open API. Nothing prevents you from using a 3rd party that connects to us. if you are an institution, we do offer Prime Services but that's another kettle of fish.
Institutional accounts get sales managers assigned to them. For complicated questions you can contact them. For basic questions it's better to just call the backoffice (I used to work for an introducing broker to Interactive). There's no per se minimum per account that I know of.