– Which strings to use?

Taking into account that in the resonant guitar (resophonic, dobro) the amplification of the sound is “mechanical”, the pressure of the strings in the cones is important.
I use 0.13 or 0.14(D), 0.17(B), 0.26(G), 0.36(D), 0.46(G), 0.60(D).
My students recommend using at least 0.11 or 0.12. Some guitarists use 0.16 first. I have used them a while and they go well for the sound with slide, but to touch with fingers is too much tension. It is best to test with what tension your instrument and fingers better respond, but forget that it sounds good with 0.9 or 0.10.
There are special games for “dobro” (sometimes hard to find) but I use normal electric strings…

– Fifth.

I will not go much deeper into the subject since on the web you will find many articles explaining what it is and how to get the fifth of a conventional guitar.
In dobro there are not many possibilities and the greater the height of strings, it is more complicated.
There is always a small margin to move the cones (in the tricone and singlecone) forwards or backwards in order to compensate for the pitch.
In guitars with spider bridge is achieved by moving the “spider”.

– Periodic Adjustments.

It is important from time to time to disassemble and remove the dust that builds up inside, to avoid unwanted vibrations. (If they have not they will never be surprised at what they can find)

I think others say that it is better to clean the strings after playing since the sweat, in some people more than in others, oxidizes. The rust on the ropes also corrodes the frets and will eventually need to be replaced.
In the same way the sweat affects the bodies of metal and wood but to a lesser extent those that have thick layers of lacquer.

If you are looking for a luthier in Barcelona I recommend you to Xavi Broussolle. Info@broussolleguitars.com
If you are in Buenos Aires: Jose Mércuri http://luthiermercuri.blogspot.com/