xVarnish and multiple PHP version questions
In preparation of the upcoming SE4.9 which is to be compatible with
PHP7, I tested some configuration changes on my VPS last weekend.  Since
I'm not a web expert, I asked the wonderful people at FastComet how to
handle this.  Current Apache on my server didn't support multiple PHP
versions, and the version update didn't support NginX (let's assume this
is correct - I'm not looking for experts here to weigh in on this
particular piece of info).  Also, I could (and now will probably have
to) run separate VPS for now, but I'm trying to prepare for the general
capability of running multiple PHP versions on the same VPS or server in
the future as I'm sure many other people do this for testing purposes).

Anyway,
xVarnish was implemented and NginX was removed.  Overall, page
access/requests seemed to be similar to previous experience, maybe
slightly faster.  BUT ... some pages were very slow to load (eg. 2.5+
minutes instead of typical 4-6 seconds).  There were 2 consistent issues
and 3-4 sporadic ones that couldn't be duplicated (so I won't discuss
these).

Login page: It seemed that the 'first time in a while'
that this was loaded in a browser, it took 2.5+ minutes to load.  Later
loads (after clearing local cache) was back to normal, until 'a while of
time' passed, then the cycle repeated itself.  This was per
workstation/browser.  I didn't pinpoint how much time had top pass
before the login page was slow again.

SEAO Google Docs Plugin:
2.5+ min to load the Plugin, and then 2.5+ min per each primary menu
item (eg. selecting a Document Category, selecting 'My Docs', selecting
'View Doc', etc.).  Unlike the Login issue above, this always was slow - every environment and every browser. 

So, all of that to ask these 2 specific questions:
1) Has anyone implemented xVarnish and experienced the above and resolved it - and if so, how?
2) What do you do/use to run multiple PHP versions on your server:

Thank you.