I hope this is the answer your looking for.. First question UDP is "send and forget" its much faster than TCP. Good for DNS, DHCP, TFTP, SNMP, RIP, VOIP etc.... TCP is a "Request/Acknowlege" connection it establishes a connection to the Computer and negotiates request, acknowelge, transmit, aknowlege, error checking, etc.. TCP is best for HTTP, HTTPs, FTP, SMTP Telnet etc...See Here and Here
The second question I am afraid I dont understand.
Traceroute works by sending a ICMP packet to the destination host. Everytime the ICMP packet hits a router a return ICMP packet is sent giving the sender the information of the router. Each traceroute sends out a sequence of packets increasing the TTL value each time. This will tell you how many routers and networks your packet transverses before it gets to its destination.
The Data packet header contains the source and destination IP, protocol information, and Packet frame size. See here