It is possible to weld cold-formed steel. The welder should be certified by the American Welding Society (AWS) D1.3 and follow AISI S100 standards. In general, field welding of material thinner than 16-ga is not recommended.
Joists or studs that bear on its flange put a compressive force into its web. In order to prevent buckling of the joist web, a small piece of the stud can be installed at the bearing location to improve the capacity.
No. Most metal clips are proprietary and have listed capacities. Another manufacturer might produce similar clips or one that can achieve the same result, but the capacities need to be checked.
You are not allowed to use the capacities listed for a manufacturer’s clip by cutting a similar shape out of angle stock. Using a cut angle stock for a clip will require that your engineer calculate its capacity.
The code does not prohibit knockouts from jambs, headers, or sills. However, they do have limitations on the proximity of the knockout to the connections. Using studs with knockouts requires careful planning when cutting to avoid having the knockout land near the connection.
Sheathing can often (not always) be used in lieu of bridging along the lengths of the stud for non-load bearing walls (exterior curtain wall).
Besides site-specific restrictions, it really comes down to personal preference. For 8-inch studs, U-Channel w/ Clark Dietrich’s Fastbridge Clip is the preferred method of bracing 8-inch studs based upon our experience and feedback with contractors.