The Magna Carta: Sigla, Ligatures, and Diacritics

I have a couple of questions for any reader who may be knowledgeable about Medieval Latin manuscripts. I have a copy of the Magna Carta reprinted from Lincoln from which I began to make a transcription. I also was using the one hosted at the British Library.

My first question is the TC question - why version is superior? I'm inclined to go with the one at the BL, but before I do I'd like to get some information first.

My second question goes to those knowledgeable with medieval manuscripts. I'm interested in the sigla, ligatures, diacritics, etc... I've compiled a short list at my forum where I'll be keeping it up-to-date as I go through the document. You can join the conversation here.

1. The elongated "a" in gra[cia] and the little & above it (the familiar ampersand - doesn't look like the Latin ligature for "et" nor does "et" fit in anywhere)


2. The 7 between Norm[anniae] and Aquit[anniae] - well, some may not draw their sevens like that, but I do [edited - yeah, this has to be a ligature for "et"]
   


3. I'm supposing the "3" at the end Abb[a]tib3 is a ligature for "us" (abbatibus). Actually, it looks more like the IPA symbol ʒ)


4. The -e in Hib[er]nie is, I suppose the shortened form of -ae; Hiberniae. Odd that the online transcription should give us thus Anglie, Hibernie, Normannie etc...

Any information would be greatly appreciated.