There are settings in UT-E of TAS-C for these-  the first tab, General, has a place at the bottom for start up company- make sure you use the format "Bxx" where "xx" is company code.  On the User Options tab, there is a display size setting.  These settings are done at each workstation.

"Remembering" of the windowed size of Evo (such as in toolbar form - we use that as well) is only available since one of the recent updates, possibly even the last one.

nope..

I just came across a setting in the IS Tech Defaults SD-Q  that the help file says:
Maximize Evo Menu Screen on Start
 
If this is set to N then each time you load Evo-ERP, it will remember the menu size saved at the last exit.  If it is blank or Y then the screen will always be maximized to full screen.  
 
You could try changing this.
 
As for the company on startup-  under PS menu there are the old classic settings for users and the system users and Passwords screen PS-A  has a place for startup company.  I would check these settings.
 
That would be the last of my guesses.

what exactly do you have in your Evo startup field?

I think it should be B.  I know for starting up in a configured company, it needs to be "Bxx" where xx is the company code.  So I am assuming that since with the default company the  xx is blank, the startup code needs to be just B.

We do our company differently here, it has a 2 digit company code, and the default company (B)has nothing but system data in it.  
But I did try here to put in a "B and a"B  " and it let me do both.  It did not take me to the default company though, and neither did the entry of my test company, BT6, take me to the test company on startup.  In fact it does not seem to matter what I put in there, even an invalid company code or nothing! That leads me to believe that something is set up on the local ISTS folder that, even when you change the startup company code, is not changing after initial setup.