Yes to all of the above

.
1. To do the text, there are two things that may need answering: Are you using 3D or 2D? If 3D, inside you do loop, you can include some kind of code like this:
rem Clear Buffer
clear entry buffer
rem Do Loop Start
do
text 0,0,""+entry$()
if keystate(66)=1 then WHATEVER$=entry$()
if keystate(14)=1 then clear entry buffer
rem End the Loop
loop
That makes it so if you press the F8 key, it saves the contents of the inputted text into a string. If you press backspace once, it clears the entry buffer, so, you have to start typing over if you mess up. More code can be added to this if you want it to just take away one letter.
If you're using 2D, you could use the same thing as in 3D, but if you don't mind the game freezing so you can input something, use this:
do
if returnkey()=1 then input whatever$
loop
That is also assuming you want the returnkey pressed. You can press backspace to erase the last letter, which is better than the 3D use, but, this freeze all game play until you press enter when inputting.
2. To change the windows size, you must use something like this (you can change the size of pixels):
rem Set Program to Windows
set window on
rem Size the window
set window size 200,200
rem Position window
position window 100,100
All of that code should be in the DB Manual.
Well, there you go.....if you need more help just post again