In my experiments with lpi, I found it necessary to reduce power as the lpi increases. A 340 lpi looks good at 80%, but up the lpi to 1355 and it burns a hole through the material.
Yes once the lines start to overlap they will go deeper unless you reduce the power or increase the speed to keep the energy density the same. Unfortunately because both power and speed are now obfuscated it isn’t easy to do that without trial and error.
It might be 0.006" beam and 0.008" kerf that I have seen but it really depends on the power when engraving. More power will make a wider line as well as deeper. If the beam was a well defined circle it would mainly get deeper (there can be some sideways spread of heat).