Not sure on the "similar objects" issue, but if your contract has been properly constructed, let the meter run and enjoy
I seem to recall that if you select one field label and this do Cmd-alt/option-A you get all similar objects selected.
However, because field labels are simply text-block objects, you may need to carefull de-select any text blocks you don't want changed which got caught-up in that selection process.
U may want to explore the idea of abandoning ship on letting filemaker's field labels serve the role of labelling fields. Depending on how self contained ur targeted landing point is, u could make an additional set of fields which would be the labels for the actual data fields. From there, there are quite a few ways to expose the label field attributes e.g. Color font size (not to mention the what the label reads).
U could create groups. Etc. its also something u can invest in for future solutions by way of including the "label engine" in ur start template.
You select all text objects (not just "field labels") by choosing the text tool from the toolbar and then "Select All" (from the Edit drop down menu).
Thanks for the hint, but it selects all objects on the screen. I must have been thinking of another application. I forgot to mention I'm doing this on a PC. I tried Ctrl-Alt-A and it selected nothing. Ctrl-A selected all objects. Maybe the Option key on a Mac does the desired action. It sure would be nice to be able to alter the css theme, similar to how Dreamweaver lets you change css.
At least on Windows, you can select any object and then hold down SHIFT and Edit > Select All and all 'same' objects will be selected. :^)
ADDED: As for modifying themes, there has been some discussion on various boards about techniques. If you do it, you could open yourself up to issues in further updater/versions of FM because modifying modifying themes isn't supported, from what I understand.
THANK YOU!!! That was what I was looking for.