Hi Stan,
#1 people who come from other twins such as the 212 are always concerned about Tq split. This is not the same on the 61. You have to remember that max Tq for take-off is 206% not 103%. So as long as you do not exceed 206% combined then you are well within operating limits. Since the 61 is usually NG limited you most often will be matching NG ( T5 if that is the limiting factor) and don't worry about the Tq split.
#2 what you are doing sounds good.
#3 You are not saying if you are landing on a deck (pad) or a runway and intend to taxi after landing. If landing on a pad then of course the tail wheel should be locked. However, if you intend to ground taxi after landing then I preferred to land with it unlocked. We had more incidents with pilots breaking pins, inadvertent collective increases, etc landing with it in than ever had a problem with it out. If you read the RFM Sikorsky does not specifically say what to do, but they assume you will land with it out as they say "if during a running landing the tail wheel shimmies, lock it".
#4 Generally it should always be off when on the ground. If you are leaving it on at an FOB for the reasons you are stating then be very vigilant and be sure to keep your feet on the micro switches.
I remember once landing on an offshore deck to wait for another deck to become available and forgot to switch it off. I was sitting there with my feet on the floor and the next thing that I knew the tail wheel started skipping sideways across the deck. What happened? Sitting on a steel deck the flux valves were affected and thus affecting the C14, so with heading hold (feet off the pedals) the AFCS was inputting left pedal to try and stay on heading.
#5 Min Tq should be 10% (on each engine). Hard engagements are not the only way to damage the freewheel units. Don't mean to be critical, but you need to get into the books a bit as there are no traditional bearings in the high speed section of the S61. The babbit bearings could care less about freewheeling, they only care about oil. What you are damaging by freewheeling is the rollers and ramps inside the units. Have one of your mechanics explain how the freewheels work in a S61 and it will become clear why freewheeling is bad.
Good luck and enjoy the queen of the skies. She is a great machine and if you treat her right she will not let you down. My favorite helicopter of all time.