You already mentioned that-twice...Funny enough, you seem to ignore the informative bits again and again.
You want to read something about EHV, OPV and EEHV? Well, most certainly!
Let me google that for you
Let me google that for you
Let me google that for you
There you go; you're welcome.
Why should I answer any of these questions to a person who openly stated that he dislikes me?
So you know you shouldn't feed Ficus spp. to each and every "browse-eaters"? Then why not mention the preselection in the beginning?
As for additional info regarding your tunnel "vision" (which is just an exaggerated fantasy version of Philadelphia Zoo's Zoo360 idea
Animal Trails - Philadelphia Zoo), I wouldn't worry that much about infectious diseases, insofar your whole dimensions, location (think climate, and due to that, necessary technology), involved species etc. (not to speak of your strange adversion against snake hooks...^^) don't hold water in real life to begin with. And do you really think that any responsible local authority in the UK (or any insurance companies) would allow you an outdoor tunnel system for large dangerous snakes?
What you generally seem to neglect in your concepts is that if (individual) animals don't want to use your tunnels, boxes etc., you will have a hard time with your non-invasive methods to do anything about that. Medical training can be an option, but is time-, cost- and labour-intensive.
If you really want to learn more about EHV, EEHV, OPV etc., come to Atlanta this year.
zoovet-conference Atlanta 2016
If you have money to offer flight tickets to strangers, then attending this joint conference shouldn't be a problem for you.
If your budget is not that big after all, then this might suit you better to get started with the basics:
http://www.esavs.net/en/artikel.php?a=1461
Otherwise:
Events : WAZA : World Association of Zoos and Aquariums
EVENTS EAZA