Well i am no expert so please dont take this as the 'only' solution.
Firstly it seem you need to clean up the existing installation. good cable's / good connectors ect. This will go a long way to making the whole thing more reliable and will remove this from causing persistent difficult to find faults.
Secondly, adding roof top antenna's to your existing WiFi should fix the range issue. its well worth drawing out a plan of the site and see if you can use direction external antenna's these boost range and increase the quality of the signal.
Even a few small UPS units on your WiFi infrastructure could be a good idea. Small desktop ones will last for ages powering a Access Point.
I would also look at getting some power points which have power conditioners/filters in them - at least to filter out some of the generator noise. you need it for your specific site but beloew is the type of thing i am thinking of.
http://uk.rs-online.com/web/p/power-line-filters/213839...
http://glocktalk.com/forums/showthread.php?t=1236747
As for getting internet to a remove site. it really depends without knowing the location. but you could look at long range WiFi with directional antenna's to the nearest town. Line of sight is the thing to think about there.
http://linkstate.wordpress.com/2011/07/05/site-to-site-...
I have noticed that survival and disaster preping web sites are quite good for homebrew solutions.