The easiest way to get a shipping quote is by simply adding the forge top your cart and clicking checkout. After entering your address the shopping cart will give you shipping options and prices before asking for any payment information.
Welding pressure varies from model to model and material to material, but generally welding is done in the 12 - 20 PSI range.
Blocking forge openings
It is really not necessary. Blocking off an opening creates higher backpressure in the firebox, which slows the flow of air into the burner. Less air means a richer and cooler flame. Blocked openings also force the forge exhaust (Dragon's Breath) out between the shell and whatever material being used to block the opening, causing damage to the shell material.
The openings are designed to be small enough to retain good heat while still allowing good access for your material.
Burner running erratically
It will be one of two things, either your gas pressure is low and the flame won't "blow through" the burner tube. To overcome the backpressure in the firebox simply blow into the mouth of the burner, like you're blowing out a candle. A quick puff of air is sometimes all it needs to push the flame through into the firebox.
If that does not fix it, you may have a small piece of debris inside the gas tube partially blocking a gas orifice. This is also a quick fix, remove the brass caps at ends of the gas tube assembly (see pic)
and blow the tube out with some compressed air (see pic). Reinstall your brass caps and you should be good to go.