1- VTP should be very carefully implemented on the network and Admin should know the impact of the same in future something happens. As if it is not carefully implemented it can destroy the network later on if someone connects the other switch to the network without having knowledge on what to be done on the switch before connecting to the network. (Advantage:- Easy of administration. Disadvantage:- If Precaution not taken it will bring the whole network down.-What I mean to say is:- if by mistake someone connects any outside switch which had conf-reg value more than the one which is in your network then that will role out the network.)
2- It is not recommended to have all the switches in the Server Mode.
3- Yes Pruning should be enabled on the links. This will help you to prevent the utilization of the links by only sending the required info out of the particular links.
4- Transparent Mode is good but you need to know why you want to move to Transparent mode. Transparent mode is nothing like running no "VTP" in simple word.
5- VTP Server/Coinet is risky option:- I agree but as I said its all depends on the Admin if he really understand the VTP impact on his network. ( Implement high level of security to prevent unnessary risk).
I have seen a large network running good with VTP as they know the impact and have implemented all the mechanism to prevent any risk to there network.
6- VTP feature it is all depends on individual. Some recommends to go with it and some dont bcz of potential risks.
During the implementation phase when you have many switches connected between each other and you know which vlans to be present on those switches, then VTP can be implemented .
NOTE:- While adding a new Switch to the Existing VTP domain:-
1- Console to the Switch and change the config register value to be 0. (Change the mode to Transparent as this will get the config reg value to 0).
2- Check the vlans on the new switch ( Show vlan) and if you find any vlans you can delete the same. ( Vlan.dat will hold the vlan database).
Please feel free to revert back for any further clarification.