Yes avoid spaces in filenames. WordPress attempts to match filename for templates. It may decide to select a php file with a space or crap out trying to find a file.
Just take it easy on your plugins. anymore than 20 is excessive. A lot of the plugins only do like a simple function and have a lot of overhead to do a simple task.
Eg your image size plugin. you can achieve with one line of code in your theme functions file.
add_image_size( 'my_800px_image', 800, 600, true );
Back when I was a WordPress beginner i used loads of plugins until i learnt the correct way after watching hundreds of iThemes tutorials.
#1 Avoid too many plugins
#2 Learn lots of CSS and basic PHP
#3 Always enable debug mode to display errors during development.
about a gazillion other things…