A water based poly will not change the color as much as shellac or varnish and should protect the finish from wet glasses or cans. You can rub the finish with a red or green abrasive pad if you don't want the finish satin or gloss .
I scorch outside and use a regular propane or MAPP gas torch (burns hotter& faster). Yellow pine works well. Practice on scraps to learn technique . Scorch lightly or full char , that's up to you. Keep wet rags and a garden hose handy. Wear heavy leather gloves. Wire brush helps clean up areas you scorch to heavy to even things out. Shellac or rattle can lacquer seals up the char from getting everywhere in the house. I wait a day or 2 before sealing if the wet rag is used to put fires out.
If you make them wider than the jaws use 5/4 or 8/4. Maple is a good choice. If you make them a lot wider use the 8/4 (I did mine about 12 to14" wide) If you clamp something off centered you need to make a stack of 1/4 MDF strips and run a bolt thru one end. Then you can swing out a number of strips until they roughly match the thickness of the part being clamped and put it in the other side of the vise. This keeps the jaws from racking and you can clamp the piece securely.