Is it possible to have 2 separate drupal 7 installs accessing the same database and can the second install be set to have access to certain content fields only but have no data entry permissions?

I ran into a problem some time ago where if modules like workbench and others were not installed the fresh install crashed. Workbench is a pain for us.

Reasons I'm asking are: -- that I need to set up a newsletter creation and mail out system that takes calendar events and dates, locations of events,, quotations, book references and some text content to be used in a view in the second installation to out put to the newsletter.

I have tried for days to get simplenews and newsletter working in a copy of the original system but there are a huge number of modules in there and something is causing the WSOD default to the Stark theme in both <Create new content type> and configurations for simplenews.

I did a fresh install of d7.19 on my home system and installed required modules for a trial. I find that simplenews and the email systems work well as expected. I'm reluctant to do anything in the original working/live system - I reckon some modules don't play nice with others but have no way of knowing.

I would appreciate help on how best to go about this please thank you in advance Roger