Run it in whatever way makes sense to your table!
Personally, I have all Boasts as going public. Secrets deeds are not Boasts.
personally i find Delving Deeper an extremely clear and runnable version of OD&D - i've been using it "in anger" for a few years now, and have only made minimal mechanical changes. it represents a very clear and concise package. i think there is a huge amount of value in going through the original OD&D books and "working it out yourself" but more as a philosophical exercise rather than seeking something you can use right now to run a game.
AC as Armour simply means the Armour Class of the creature being described is equal to whatever armour that individual is wearing - likewise for Damage as Weapon.
This was originally written for use with Original Dungeons & Dragons (OD&D), using the retroclone Delving Deeper which is a cleanup and restatement of the original text. You can find digital copies of Delving Deeper online for free. Notably, OD&D and many of its derivatives use a d6 for all HD and most damage - any increase beyond a flat d6 represents a monster able to deal damage beyond the limits of a human.
Additionally, my own work, Wolves Upon the Coast, uses this as the only monster manual.
Hope this helps!
wikipedia has a pretty good discussion around hillforts - you can extrapolate what some of the cultures of Wolves might have developed on top of that.
beyond that, a lot of fortifications would likely be a mix of wood and stone, based upon the roman fort model - the low population count makes large stone fortifications very difficult, potentially limiting this to mostly an outer wall. in a lot of the map, some of the roman fortifications would still be standing.
when i've run it magic is mostly discovered by doing work for existing magic users, or learning it from any of the grimoires found. there is also the possibility of learning some magic from one of the demon-faced coins.
i've heard some tables leave the spell lists accessible to the players so they are instead actively seeking the ingredients rather the knowledge of the spells. personally i prefer having it all hidden, but you know your table best.
similarly, i'd shy away from starting with knowledge of magic but as above - you know your table best.
This guy discusses his experience with throwing replica franciscas (frankish hand axe) - might be useful
https://www.youtube.com/watch?v=CcCbL_y3zTM
herein lies a path to leave mortality behind
https://lukegearing.blot.im/wolves-upon-the-coast-hexfill-procedure
These are just the ones off the top of my head - I keep a list of everything I've read since some point in 2021, you can see it here
Use the more specific weather (i.e. the inland table) if you feel like they are conflicting. The naval weather table covers all of the sea, and acts as more of a fall-back or addition to the in-land specific tables. If the players manage to sail out from the under the storm, they might find the light breeze prevailing upon the ocean - or it is more of a rainstorm, meaning weak winds.
1) Yes this is the intention.
2) That would depend on the specific situation - any one of the suggestions you made could work. Wrestling an enemy down might mean a STR check (using the sliding difficulty depending on the size of the foe) whereas a weapon leg sweep might be roll-to-hit followed by a Dodge Save. Part of the system's design is giving you multiple points to use to adjudicate situations as you see fit.
3) Correct, although this was expanded on a little in the April update - make sure that's the file you're working from.
4) The chances are in the Magic book, updated very recently - make sure you're working from the most recent update.
They can be used in the OD&D alternative combat matrix.
The penalty is applied to attacks against the one wearing the armour - this is done for systems (such as Wolves Upon the Coast) where AC is never modified due to being used in multiple rules. If your game of choice only uses AC for protection, you're fine to use the 'normal' statistics and ignore those in italics.
You can get it alongside a number of other creations also using Violence here.
You also get a sticker.