Hi binhexoctdec,
With regards to your first point:
If you want to populate your table, then...
1- I assume you have either a shapefile or a table whose points you have displayed as x/y coordinates. Either way, your shapefile should have a projection system defined.
2- Right click on the dataframe (by default called Layers) containing your shapefile and select Properties
3- Select the Coordinate System tab (note the current projection may be that of your shapefile if it was the first thing added to your dataframe)
4- Under Select a Coordinate System, open Predefined, followed by Geographic Coordinate System (i.e., you are switching from a projected system to a geographic one)
5- Choose a Geographic Coordinate System (GCS) best suited to your dataset (if for instance you were using a North American Datum 1983 (NAD 83) for your projection, probably best to stick with the same datum for your GCS system)
6- Click Apply
7- Select the General tab, and choose the Units display as Decimal Degrees, click OK
8- Right click on your shapefile layer and select Data > Export Data
9- Specify "Use the same coordinate system as the data frame" and specify where you want to save your new GCS shapefile
10- Once you've added the new shapefile back to the map, click on the ArcToolbox icon (red tooolbox near the top) to open it
11- Open Data Management Tools > Features > Add XY Coordinates
12- Specify the GCS layer in your drop down list
13- Right click on your GCS layer and select Open Attribute Table
14- The POINT_X and POINT_Y fields will contain your equivalent coordinates in Decimal Degrees
15- If you want you can populate the fields you had already created to hold these values with these 2 new fields
If however, you want to avoid this process, and this is just for visualisation with the Identify tool, then you don't actually have to populate any fields in your attribute table.
1- Select the identify tool
2- Click on your point: the location's coordinates are displayed along with the attributes in the fields for that record
3- Select the little drop down arrow to the right of Location, and select Decimal Degrees (or any other unit for that matter of your choice). Now your Location's coordinates appear in Decimal Degrees
With regards to your second question, I'm guessing your structures have hyperlinks where clicking on them will open an image. Quite often hyperlinks for features are best stored in a field of that feature class' attribute table. I suggest you look there for starters. If you notice for instance that there is a field which contains the hyperlinks, then you could always do a Select by Attribute, and select all records in that field that say aren't blank. In essence that will select all the features with a hyperlink.
Hope that helps.
