I'm new to this forum so I apologize if I'm asking a question that has already been asked and answered. So with that I'll ask:

I purchased some furniture (two end tables and one coffe table) that were a soft wood - probably pine. They were made in mexico and were "rustic" (old metal hinges etc). I liked the look but didn't like the finish so I sanded them down to bare wood and refinished. I used a sanding sealer and then applied three coats of a stain until I got the color I wanted. I can't remember if I used an oil based or water based stain. After that I used a satin polyurethane finish (two light coats). I did sand inbetween coats with 400 grit sandpaper.

I got the finish I wanted and I am happy. However, I have had some cracks form in the wood itself, not the finish. I know that with other forms of finishes you should use a wax, oil, or other furniture type finish to maintain the wood. My question is do you have to use a furniture polish, oil, wax etc for a polyurethane finished piece? If so what should I use? If not, how should I care for a polyurethane finished piece and do you have any recommendations on what I should use to fix the cracks in the wood (caulk, wood putty, water putty etc)?

One more question - I just got engaged and my fiance has some high end bedroom furniture. I wanted to make sure it was taken care of but I don't know what to use on the wood (bed, dresser and nightstands) because I can't tell what type of finish is on these pieces. What I do know is that it isn't polyurethane because it is high end furniture. Any advice on what I should use on these pieces to make sure they keep looking good and last? Thanks!