Hello, I'll try to help...but remember, I'm a beginner also...
For #1, can you explain how it's "changing"...and I don't insult people so don't worry, and I hope others don't insult me either if I do something wrong.
Constructive criticism is a much better way to learn.
As for the colors of the title bar:
...you might want to change the details of your xfwm theme: http://wiki.xfce.org/xfwm4_theme_howto
style "titlebar" = "default"
bg[SELECTED] = "background color of open window"
fg[SELECTED] = "title text color of open window"
bg[INSENSITIVE] = "background color of the windows that are behind the open window"
fg[INSENSITIVE] = "title text color of the windows behind the open window (doesn't change the closing buttons of the xfwm pixmap theme...you must change your xfwm window theme for that)"
widget "xfwm" style "titlebar"
class "MetaFrames" style "titlebar"
widget_class "MetaFrames" style "titlebar"
for #2, that is a good question, as the names on "thewidgetfactory" are: ComboBox and ComboBoxEntry...but they aren't in my gtkrc, or any Xfce gtkrc that I have looked at.
I know that I make the ComboBox match with this part of my gtkrc:
style "colored" = "default"
xthickness = 2 # Affects the Thunar Path Box as well as other things.
ythickness = 2 # Affects the Thunar Path Box as well as other things.
bg[ACTIVE] = Active button on panel handle, selected background color when clicking any app button, (not Firefox), ComboBox Drop down menu arrow button bg.
bg[PRELIGHT] = Rollover background color (hover) on all buttons and drop down menus.
fg[ACTIVE] = Font for active button, ComboBoxEntry drop down foreground arrow.
fg[PRELIGHT] = Font color for all selected buttons (roll over) except ComboBox and ComboBoxEntry (only arrows), Also font color for all rollover drop down menus.
text[ACTIVE] = Old highlighted font (like if you highlight text, and then click on a different window, the text color and bg color will change. This is for the text foreground font color for the base[active] background color. (basically, "active" is like a folder that is opened before opening the next folder which is base[selected] and text[selected] )
text[PRELIGHT] = ComboBox and ComboBoxEntry font color.
smooth_edge = true
grip_style = slide
fill_style = gradient
orientation = vertical
shade_start = 1.24
shade_end = 0.83
# I changed the "fill_style = plain", to "= gradient" for the rollover buttons.
# It affects drop down menus in Firefox, and other menus. I chose "orientation = vertical"
# try "orientation = auto" and see if you like it.
# auto will draw the gradient sideways sometimes.
# Also mess with the "shade_start" percentage numbers
# and the "shade_end" percentage numbers for different affects.
widget_class "*List*" style "colored"
class "*List*" style "colored"
widget_class "*Text*" style "colored"
class "*Text*" style "colored"
widget_class "*Entry*" style "colored"
class "*Entry*" style "colored"
and for #3, I don't know how to change the size of the arrow, and it seems that way in most Xfce themes also.
All I know how to do is change the colors of the arrows and the backgrounds of it...and that is in that section above...in the: style "colored" = "default"
and I think you know that part good because all of your colors match....
....as for your 4:20 theme, I can tell your close button is a weed leaf, and your minimize button is a bowl, but what is your middle button on the right? Is it a heart?