1. there isn't at the moment. possibly when Lua isn't beta anymore Turbine will embad similar system that plugin loader into the client making it all easier.
you can however make a shortcut for the manager: /shortcut X /plugins load manager
(x any number between 1 and 72, 1 is the first quickslot on the main quickslot bar). this will add a skill type button on your quickslot that you can simply press everytime to log into the game and the plugins will load. it can also moved around like a skill after it's created.
alternatively you can shorten the command with alias command:
/alias ;man /plugins load manager
(;man is example, can be any word you choose, but remember the semicolon in front of it)
then you can just type ;man anytime to load the manager
2. I'm no Lua expert so I let the smarter people to answer this. Itmay have to do with the Turbine's plugins examples if the plugins has dependency on them. more at here
3. Sounds like you only forgot to relog after selecting the skin. Every skin mod that modifies panel/etc sizes require you to relog after selecting them for the first time, no need to do that more than once if you don't change to another skin. You still need to do this with every toon you use it however.
Hope that helps.