Lots of photos at say f8, or your best aperture. There is no particular punishment for too many photos, but you can suffer focus gaps with too few.
Indeed, but if this is something that has to be done on a regular basis, then investing in a focus rail type of setup will pay off (length depends on the size/depth of the subject to be shot). With close-up and macro, depth of field (DOF) will be limited, but also simple to calculate using a formula that uses the magnification factor as one of the inputs. With a focus rail, the magnification factor remains the same, so the DOF range is a constant. All that needs to be done is calculate the step interval to make the rear of the DOF zone match the front of the next more distant interval shot. An ideal COC to use in the DOF calculation would then be equal to the sensel pitch.
I don't believe Helicon works on raws. Lightroom exports tifs to Helicon. Process your raws fully before submitting them as tifs to Helicon.
Helicon Focus does process Raws, by the use of DCRaw. However, first processing the intermediates to TIFFs or JPEGs does give more control, e.g. it allows to remove Chromatic Aberrations if needed. Other than Capture sharpening, I wouldn't spend too much effort on processing the individual focus brackets, because only a relatively few pixels will be used from each one. It does pay off to remove sensor dust spots, because they will turn into very noticeable trails in the final image. Helicon Focus Pro does offer a Dustmap feature, where a single dustmap image will remove the dust from all frames in the stack, however, this is an operation best done at linear gamma, so that would be in the linear Raw converted stage, or on at least a 16-b/ch file that can be linearized during the operation without too many quantzation/rounding errors. I remove my dust spots in Capture One Pro, but when I tried it, HF alo did a reasonably good job.
If you have sharp, high resolution originals try B 4 2 or A 4 2 to start. I think default is B 8 4 or something a little less tight than that. Default works fine too. It's worth an hour of two of experimentation to find the best settings. Not really very critical for most subjects. Bramble-bushes need the most carefully chosen settings, hard edged architecture will be much more forgiving.
Yes, it is subject dependent (occlusions are potential troublemakers, although shallow DOF brackets can help when there is lttle subject motion), but with straight edged subjects and sensel pitch aligned DOF zones, the Radius can be very small, even a B 2 1 setting can work well in such a scenario. A tightly controlled setup at the start, will pay off later in the stackng/processing.
Great program, I use it all the time.
I'm also a long time satisfied user of the program.