Re the pressure gauge
You can fit an in-line gauge no ptoblem, but in time you just get used to it so you save money.
Fully on will give more then 500psi from what I am told (mines a earlier version with 300psi).
Most of the time you wont be going over 300-350 anyway.
For hand tool use probably around 150ish ie suites
You will know from experiance what the right setting is - like Jim says - what are numbers anyway (just indicators).
Hose management.
The hoses from Solutions are very flexible - be thankful you got them from them!
Have you a 100ft ie 2x50!
I cut one of mine into15' and 35' so I have 15, 35, 50, 65, 85, and 100'. Dont forget you need 2 mor eend pieces!
Many houses you can manage with 50' or less so if you use the 15 and 35 you can redue as you work yourself out of the house. Many times you will only need the 35'.
I also have a 10' piece of 1.5" to connect to my 1.5" wand (maybe you got the 2" wand)
This gives more flexibility when working in tighter spaces like bedrooms with all the furniture in or suites. Although for suites I have a 25' piece of hide a hose (solution hose indie the suction hose) - less chance of snagging on the suite.
Using this 10' along with the 15, 35 and 50 gives you many more combinations.
You get used to coiling them up - its the solution hose that I find greater problem with - but lay it out straight preferably when still warm and it gets easier.
Enjoy your Scorpion.