I can comment but it's based on Australia. I've just completed my CSWIP 3.1 to get a welding inspector qualification. We have a local system here that seems to be more highly regarded by locals but CSWIP is an international one so commonly asked for. It is also a quicker course as far as I...
I would go for the o-ring, as stated previously it's easier to tell visually that it is assembled properly. There is a range of modified B16.5 flanges called ASA flanges that have o-ring grooves in them.
Is your loading on the bolts concentric or eccentric? If it's concentric then you can assume the bolts carry the load evenly, if not you need to translate the force using either the elastic method or instantaneous centre of rotation (ICR) method, both of which end up with some bolts carrying...
If you search for deposition rate a few decent sources come up, the TWI and ESAB ones cover most of what you're looking for. There are also numerous books, I find the AWS - Welding Handbooks pretty good, ASM also has some good material but if you get their stuff be careful as they duplicate a...