I know we've discussed adding extra information to markers before. Definitely something that interests me and a SALUTE of commonly added info might be useful. Something to consider for 0.7.0 though, since I can't change the data structure of messages without making the new version incompatible with the current 0.6.0 version that doesn't use this extra data.
It does make sense to keep deleted items in the log, at least for a little while, since although one of SPON Map's significant features is that it does tell you who placed a marker and when (and will, when I implement dragging, tell you who last moved it!), if a marker disappears in-game, you don't know who deleted it. Not sure of the exact way to implement or show this, but yes, I agree to this suggestion in theory. In the mean time, I suggest you try to "aim" your markers at only those you want to see them, so that you are less likely to have other people delete them. Remember that with SPON Map you can send a marker to an individual, another group or just to medics (among a lot of other specific targets) so you shouldn't have to send "side" messages very much any more, which can be seen and deleted by anyone.
I assume by deletion reports you mean a text message when a marker is deleted, just as you get a message when an urgent marker is placed (place a marker with text beginning with an exclamation mark, such as "!Tanks here"). This is certainly possible, but I prefer the idea of a less intrusive logged message, rather than spamming even more into the text chat.
I have considered disallowing deletion based on rank, but that could cause problems if your colonel disconnected after drawing on the map. No-one would then ever be able to delete those lines (even if the colonel reconnected, he wouldn't see the lines he drew, since SPON Map isn't JIP-updating yet, so couldn't delete them).
I have no idea what you mean by "disabling of in game text".
I did have 8-digit support knocking around at one point for those maps using 6-digit coordinates (and 6-digit coordinates shown for regular 4-digit maps), but I removed the feature, since I didn't want it as a default, fearing it would be considered an easy-mode. As you say, though, you can easily use the "realistic" method of using one of the grid overlays to work out the extra digit of accuracy anyway. My priority, for now, is to make sure that the coordinates given by SPON Map are accurate on all possible maps in the game (I hope this is true now, since SPON Map GPS values are based on reading map config, rather than knowing info about a specific list of maps, but I'm sure someone can find one that has unexpected config info in it). Not really sure when, or if, I'll reintroduce extended GPS values, but the more people that want it the more likely it will reappear (though it won't be a default setting).
I don't have any plans to integrate a unit tracker into Map. When I implement marker dragging, a manual tracker would effectively have been made, for example. You could also use a detection-based tracker like SPON Sensor or SPON HoloMap. SPON Map doesn't really know anything about your command structure (unlike, for example, SPON Status), so again, I don't really see that it is an appropriate Map component. Map is also MP/COOP focussed but a tracker is relevant in SP missions.