The grid in Studio is how you check scale -- you can use it at specific units (in the preferences) and also with any of the orthographic camera views to check scale.
I've had 3DS files come in absolutely huge

-- sometimes this is a units issue... Maxwell always works in Meter units.
If you have a 3-button mouse you can zoom, pan, and rotate (as well as camera specific movements) using the different mouse buttons in combination with the modifier keys depending on what specifically you want to do... I use a Wacom tablet which I've programed buttons to mimic those commands. Check the Maxwell manual for specifics as it is a long list of functions and key combinations (or watch my Maxwell 2 series videos in which I cover all the Studios functions).
I'll answer your other questions it a bit later when I get into the studio ( I just got up)... I also don't have Maxwell here and I always like to double check myself before giving specific instructions.
Maxwell Studio is much more powerful than Sketchup but along with the power comes a learning curve but once it is mastered you may find that you will prefer it to Sketchup in many ways for setting up scenes (I certainly do). We'll get you up and running ASAP, so don't get too frustrated
Best,
Jason.