for each of the ground force units ie at what distance they start firing there weapons from the enemy and whether target a particular type of target first. This would include tanks, mortars ...........

There is actually a thread of FAQs over at the Eagle forums which address this. I cannot think of the address off hand but I know it is still there because I use it when building missions. Generally, from what I remember, tanks and IFVs will fire on an enemy when 1km away. Artillery is listed in those FAQs.

You can go into F10 View and turn on threat circles and use the measurement tool for distance...

Here are some links -
RWR & Threat Position
The guy Malexa writes a very interesting post. I will try his second solution, but he says 'create a flight plan out of these Mark Points'... manual Pages 467-470 gives clues.

This looks very nice -
toby23 Document Pack For A-10C


WC

Here's another -
War Hawks A-10 Checklist

WC

Thanks mate for all that

SAMs and other arty pieces have engagement ranges, but tanks and BMPs do not. From experience, BMP-3s open fire at 1.5-1.8nm out and T-80s from 0.6nm or so. Other armored vehicles or older tanks/BMPs may have shorter ranges.

Also note that while you may be in the engagement range of a SAM, it will not necessarily fire at you from that range.

I've always wondered where they got that pic on page 22.