Item 1: I conferred with Lynnette Taylor and she suggests that these contents be done as an index, even though these are not in alphabetical order. The idex format will accommodate these page numbers and will also resolve the issue of the span of page numbers across more than one volume. It will be necessary to braille the entire contents at the beginning of each volume. I think you could write a TN for the first volume only to explain that the table of contents is brailled in index format to accommodate the long page number entries and that the complete contents will be in each volume. See the bottom of page 39 in Formats for contents in index format.
Also in the contents--the fifth item--Palabras con n antes de ... etc. I notice that there is a handwritten notation that indicates italics. Italics should not be added where not present in print. The other freestanding letters in this contents entry are in italics. These should also be italicized in braille. See. 3.1b again. Italics retained for freestanding foreign letters.
Item 2: Is there a question here? If you are asking about something about the r, I don't understand what it is. You have stated that symbols of enclosure are used in the contents, but apparently not in the text. Since you have not included the text page, I can't tell that. In any case, I don't understand if you are asking about something. Please let me know if you have a question about this and I'll be glad to try and help.
Item 3: Yes, the letter indicator should be used with all syllables. See 1.6b(2). The new foreign language rules require the letter sign for all word parts, whether preceded by a hyphen or not. Use the letter sign and follow print for emphasis. The letter sign will follow the typeface indicator, if present. See 1.8 Order of braille composition signs with foreign letters or words.
Item 4: Yes.