I'm about to start the replacement of an old deck and was wondering if you
guys can answer a few questions for me.

1) I've reclaimed some old and heavy 10" x 10" posts from a barn that I'm
hoping to use to give the deck some character, does anyone see any problems
using this structurally?

2) What type of sealer should I use to treat this old lumber.Recommendations

3) I need to bury some posts this weekend and I'm not sure what the best
method is. Do you get a concrete tube and fill it full of concrete and then
put the post on top or do you encase the post in the concrete? WHY?

4) Should I stick with treated lumber for the posts?