Answers

I doubt this was Sikkens. It is not that hard to remove. You should be sure to apply a borate treatment before you stain. didn’t get all of your question, but sanding is OK.

20/40 will work and you will get about 60 to 70 sq ft per 40 pound bag.

get your sander or grinder out.

Do not know of anyone directly in the area. Call Mike at 866-670-3020.

not sure on this one.

If prepared properly, treated wood will stain up just fine.

Call Mike at 866-670-3020.

sanding is a good option , but slow. yes, you can use the same stain

Call Mike at 866-670-3020 for help and answers.

Call Mike at 866-670-3020.