You can use a laser pointer and a level to figure out which way the
land slopes pretty easy, just tape it on top. You may need to use a longer pipe or piece of wood to get a true reading.
Going to be hard to get it to wick up from exterior. Wicking beds pull up from directly below, that is how we are building our hegels out west, basically wood filled pits.
Swales would just be to direct the water and let it seep in, as you said.
Best bet is to dig around the outside base of the planters, put in
pea gravel, and just a thin layer of mulch. i would put some boric acid on the gravel myself.
if just wood chips, you are going to bring in and harbor lots of pests, and i know of no good bugs that live in deep mulch......
you would just be keeping the lower soil moisture there, wouldnt help much but the deep rooted stuff, but will cut down on the raised beds dehydrating.