Hi there,
Sorry for the delay in seeing your message, I do not regularly check this part of the forums.
All triggers use some degree of margin, usually the +/-100ft you mention, sometimes more or less depending on the situation.
If you have the latest version of VFR then visual markers will be displayed automatically.
Please see here for all the info on the FS ACADEMY range, including support here: www.fsacademy.co.uk