> TCP segment go inside IP packets,there are many problems
I really do not understand that statement. Yes, transport protocols, like TCP, are the payload of network protocols, like IP, but that is how it is designed, not a problem.
> IP packets get queued in intermediate routers and can delay their delivery to the destination?
Yes, it is possible that packets get queued when there is network congestion. Queuing can cause delay, but the alternative is to simply drop excess packets in congestion, and that can be worse than delay.