Let's go through this slowly
There is no prohibition on Ritual spells, as it's a magical effect you could produce "through some other means, usually a Supernatural Virtue or the Hermetic Arts" - however, it goes on to say "First, the character may forgo any necessary words and gestures or other actions when producing an effect with his powers, without penalty. Instead, he crafts a physical object, which takes the place of the spell" - so the craft magic replaces ceremonial casting. I would say none of the ceremonial bonuses apply when using Craft magic.
If you work on a carving and then leave it - as you "Must avoid distraction and maintain concentration whenever he is working on the object, just as if he was casting a spell, and like casting a spell the character can only work on a single object at a time" - so if you partly finish something, then try and cast a spell, it would surely count as "casting another spell" under the concentration rules on ArM5 p82, requiring a Sta + Concentration + stress die roll of 15 or more. Therefore, unless you are a genius at concentration you make casting any other spells while you have a partly finished object extremely difficult. In fact, this points to a weakness of craft magic - if you're half way through making your magic horseshoe, and an emergency occurs in your forge, you have to decide whether to drop all the work you've done and start again later, or to try casting with the EF 15 concentration roll.
I would say you don't need to worry about the 15 minutes/level applying while crafting, as many crafts take longer, but you do need to worry about all the distractions and continuing situations mentioned in the table on page 82 of the core rules.
Does this apply to spontaneous, formulaic, ritual and any other casting? Well, as it says "usually a Supernatural Virtue or the Hermetic Arts" it will definitely allow you to reproduce anything you can do by Hermetic effects, and by saying "usually" that does mean it's possible you could use other magical methods with it. However, as with any other combination of effects, it probably requires your SG to rule whether a particular combination is valid.
I think the stress die roll is a casting roll and not a craft roll, as it says "If the effect would normally require him to roll a stress die" so you roll a stress die as normal if it's a spell that would normally need one.
The craft chosen doesn't need to reflect the technique and form - however, if they don't obviously go together the effect looks blatantly magical. If I put a damaging effect into an arrow, and then fire it at someone, when the other person looks incredibly hurt it might be down to the archers skill or a lucky shot. If I put a damaging effect into a bread roll (using baking as a craft), and throw it at someone who starts bleeding, then I'm obviously being magical.
Can it be MuVi'd and ReVi'd as normal? As always, it's up to your SG whether you have sufficient understanding - ArM5 p 159 in the MuVi guidelines says "These spells can only be used on Hermetic magic, as they depend on a good understanding of the processes involved". If your SG says this sort of magic is insufficiently integrated into Hermetic Theory, then you will need a breakthrough before you can MuVi craft magic effects.
How does this interact with Multicast Spell Mastery? Well, it counts as a single casting as one of your magical effects, so if you can cast a spell and multicast it like crazy, then theoretically you should be able to apply this to a Craft Magic effect. I don't combining these will break the game any more than high levels of multicast mastery would do anyway.
So much work just to get through section 1. This will take a while to get through. I tried making a Rusticani once, but it can be hard to see how to use their powers well.