1. Yes in fact I strongly recommend it over the square as squares can be very finicky. Saturn Square might be shortest but the Square in particular of Saturn can provide negative principles. It's not 100% whoosh negativity but potentiality of it. Squares are advanced and a number of members have replied at least one but sometimes two on certain ones provides life changing results. Of course a good affirmation is needed and much like Lydia mentioned spending a solid 10-15-20 minutes visualizing as the Square is a potential dynamo of energy that requires good imprinting. I suggest the Runes over the Square particular to Saturn. IF you want to mess around with it okay up to you but it's better to be safe than sorry. Sometimes the effects of the Square manifest over time and continue to do so over time. So it might not be right away but overtime plus they affect the Astral Chart even if it's material or spiritual but working for a different goal. At least that is what some have mentioned IF you want to directly mess with the Astral Chart you can have that options.
Again I suggest stick to the Runes in fact I performed a Saturn Square 2017 or 2018 in my time. And besides a Venus square that I regret not so much Jupiter and Sun. I'm kinda wondering what I was doing and should I have done it, most likely I should have just used Nauths.
2. Nauthiz and Runes in general are very docile and worst case scenario they are a slap on the wrist. Also some people respond better to Runes than others also some people respond better to certain runes vibration types than others. For example I like Gothic version some runes work better in multi-language for example despite using Bairkan Gothic, Bjarkan seems powerful because at least three European alphabets of the spiritual type use it for Rune working.
Also I forgot to mention Runes are Sublimated versions of the planet like I said worse case scenario, slap on the wrists. In reality Nauthiz is a very good Rune and I think every Satanist should use at least once but a few times run a handful of 40-day scenarios.
3. Blitz can shed light on this more so. Yes it's possible but I think Nauths is more of a scenario maker rather than a basal chakra enhancer. See here is the thing, would your rather work on the base chakra which posses various vibrations of the chakra system itself and work on things like physical exercise like Yoga(Hatha) a bit with K-Yoga and exercise such as working out. Or would you rather work solely on spiritual and hope for the best.
I think from all the things Blitz has told me I get the thoughts and feelings it's better to focus on using Saturn as a realism, grounding, centering, and stabilizing element rather than outright the base chakra.
Yes it's important to work on the base chakra not for the Kundalini I think too many want high and mighty spirituality. Think low and slow, I think Nauthiz is better served generating towards undelusional working focusing on realism akin to grounding, centering, and stabilizing the Soul as a whole.
But honestly after spending time investigating and reading on Nauthiz my best affirmation I've come up with in my overthinking is.
"Nauths is fully grounding, centering, and stabilizing me to reality forevermore in best ways for me".
I think simply what might be is work on your base i.e. meditation, vibration while simultaneously working on Nauths. I think the idea is the base while extremely important especially to eliminate delusion and add to realism. It's more of an internal prospect rather than Nauths generating realities. Both can do stuff both have been stated to do things. But both compound each other.
On top of that Nauths can be used for discipline so you could potentially add to the affirmation I provided a disciplinary aspect. Not discipline in a hostile manner but a gentle manner of slowly building up an iron-strong will of activity. For example doing meditation and focusing on it everyday or exercising the necessary amount.
Again Nauths is the realm of reality Saturn the lead the property of life and it's rules and regulations.