With respect to wood raised beds, your best option would be to use wood like cedar which has great longevity.  For other wood not so rot-resistant, you could instead line the beds with landscape fabric or plastic.   If you use plastic, ensure you have numerous holes in the bottom to enable proper drainage.  You could consider sealing the inside with a food safe product like EZ DO Food Safe Coating.   You can also consider raised beds built with steel, galvanized metal (sheep & horse troughs), masonry.  

Sealing terra cotta pots can be accomplished by first cleaning the pots, inside and out, and letting them dry.  Next apply 2-3 coats of available terra cotta sealers, exterior varnish, or something like Thompsons Water Seal (you can get this in a spray can).  Apply to inside and outside including the bottom.   If you intend to grow any food/herbs, ensure product is marked safe for this purpose.