Q:

Relativity, Time Dilation and multiple reference frames

I am doing some hard sci-fi worldbuilding and really want to get as much correct as I can, but the effects of high sub-light speed travel on the travellers is doing my head in.  I've pored literally over 100 hours over reading, video and podcasts on time dilation, special and general relativity, the twin 'paradox' etc etc.  Most of these sources are particle physicists of some kind but I'm getting conflicting or incomplete information (also entirely likely I've just not understood).  So, here I am praying for your help!  I don't need the math, just a clear understanding of the physics. 
The Context:
3 people on a space station travelling at a constant velocity.  Emily, Max and Beth.  Dave is on a distant planet.  Assume no acceleration for anyone at the moment. 
Emily remains on the space station. 
Max travels away from the space station in a straight line at 90% light speed.  His destination (Dave) is 10 light years away. 
Beth travels away from the space station in a straight line at 70% light speed, but at a 45' angle to Max. 
Question 1: (One-way with constant velocity)
When Max arrives at Dave, what time has passed for Emily, Max, Beth and Dave? 
Question 2: (Return with constant velocity)
Max reaches Dave and immediately returns.  When Max arrives back at Emily, what time has passed for Emily, Max, Beth and Dave? 
Question 3: (One-way with acceleration)
Max and Beth accelerate at 1G. When Max arrives at Dave, what time has passed for Emily, Max, Beth and Dave? 
Question 4: (Return with acceleration)
Max and Beth accelerate at 1G. Max reaches Dave and immediately returns.  When Max arrives back at Emily, what time has passed for Emily, Max, Beth and Dave? 
Here's hoping you clever-cats can set me straight!  Many thanks! 

A:

Q1: Outbound trip 10ly at 0.9c with one a potential observer at 0.7c

Max arrives at Dave's location in 4,055 days, according to Dave's clock.  Dave is 4,055 days older.  If Max sent a message at light-speed informing Dave of the journey, Dave received this message only 405 days ago.  
Emily has also counted 4,055 days pass by since Max and Beth left.  If Max send an "Arrived Safely" message at this time, it will be another 3,650 days until Emily receives it. 
Max is 770 days older than when he began the trip.  
At this point in time, Beth is 2,068 days older 

Q2: Return trip at 0.9c with potential observer at 0.7c

When Max returns to at Emily, she will have counted off 8,110 days since Max initially left, according to Dave's clock.  Emily is 8,110 days older since Max embarked on the trip.  If Max sent a "Coming Home" message at light-speed informing Dave of the journey, Emily received this message only 405 days ago. 
Dave has also counted 4,055 days pass by since Max left for home.  If Max send an "Arrived Home Safely" message at this time, it will be another 3,650 days until Dave receives it.  If Max has been diligently communicating both ways Dave would have counted a total of 4,460 days between Dave receiving Max's "Coming to See You" and "Arrived Home Safely" messages. 
Max is 1,540 days older than when he began the trip.  
At this point in time, Beth is 4,136 days older 

Q3: Q1 with 1g acceleration (rounding 1g to 10 m/s/s, and rounding c up to 3$\times 10^8$ for my own benefit)
(also assuming relativistic effects on mass don't cause the engines to provide less acceleration)

Beth arrives at her cruise velocity of 0.7c in 21 million seconds (243 days).  Roughly 213 days have passed for Beth.  
Max arrives at his cruise velocity of 0.9c in 27 million seconds (312 days).  Roughly 248 days have passed for Max.  During acceleration, 0.385 light-years of the total trip distance were traveled.  

Max will cruise the remaining 9.24 light-years in 3,747 days relative to Dave and Emily's clocks / 712 days on Max's clock.  
Deceleration on arrival takes an equal 312 days as Dave or Emily would measure it, but only 248 as Max would measure it.  
The total trip time, then is : 4,371 days as Dave and Emily would measure it; 1,336 days as Max would. 

Q4:

Beth continues at her cruise velocity unchanged. 
Max accelerates and decelerates for the first and last 312 days of the trip, counting only 248 days on his own clock for the speed-up and slow-down.